Algebraic Fractions (Equations) - GCSE Higher Maths
Summary
TLDRThis instructional video teaches viewers how to solve equations involving algebraic fractions. It begins by combining fractions on the left side of an equation using a common denominator, then simplifies and solves for the variable. The video progresses through multiple examples of increasing difficulty, including those with quadratic equations that require factorization or the use of the quadratic formula. It concludes with solving equations with complex denominators and provides a step-by-step approach to finding the solutions. The video aims to equip learners with the skills to tackle a variety of algebraic fraction problems.
Takeaways
- π The video is a tutorial on solving equations with algebraic fractions.
- π It builds upon a previous video titled 'algebraic fractions operations', which is linked in the description for reference.
- π The initial step involves focusing on the left-hand side of the equation and combining fractions by finding a common denominator.
- π To combine fractions, the video demonstrates converting each fraction to have a common denominator, often the least common multiple (LCM) of the original denominators.
- π The process includes multiplying both the numerator and the denominator by appropriate factors to achieve the common denominator.
- β After combining the fractions, the video shows how to expand and simplify the resulting expressions.
- π’ The video provides step-by-step solutions to various equations, including multiplying both sides by the denominator to eliminate fractions.
- π It explains how to handle equations with quadratic expressions, including factorization and the use of the quadratic formula.
- π― The video also covers how to deal with equations that result in a quadratic that does not factorize easily, requiring the quadratic formula or completing the square.
- π For complex equations, the script illustrates the process of expanding brackets and simplifying terms before solving.
- π The video concludes with a series of examples that incrementally increase in difficulty, guiding viewers through the problem-solving process.
Q & A
What is the main topic of the video?
-The main topic of the video is solving equations that contain algebraic fractions.
What should viewers do if they are not familiar with algebraic fractions operations?
-Viewers should check out the previous video titled 'algebraic fractions operations' which is linked in the description of the current video.
What is the first step in solving an equation with algebraic fractions according to the video?
-The first step is to focus on the left-hand side of the equation and combine the fractions into one fraction over a common denominator.
How is the common denominator found for fractions with denominators 6 and 4?
-The common denominator is found by determining the least common multiple of the denominators, which in this case is 12.
What is the process of rewriting fractions over a common denominator?
-Each fraction is rewritten by multiplying both the numerator and the denominator by the factor needed to reach the common denominator.
How does the video handle the right-hand side of the equation initially?
-The right-hand side of the equation is left alone initially while the left-hand side is combined into one fraction.
What mathematical operation is used to simplify the numerator after combining fractions?
-The video uses expansion of brackets and then collects like terms to simplify the numerator.
Why is it necessary to multiply both sides of the equation by 12 after combining fractions?
-Multiplying both sides by 12 eliminates the fraction and makes the equation simpler to solve.
What is the solution to the first example equation provided in the video?
-The solution to the first example equation is x = 27/5, which is 5.4.
How does the video approach a more complex equation with denominators 6 and 9?
-The video uses the same approach of finding a common denominator, which is the least common multiple of 6 and 9, and then combines the fractions on the left-hand side.
What is the common mistake to avoid when expanding brackets in equations with algebraic fractions?
-The common mistake to avoid is incorrectly handling the signs when multiplying terms, especially with subtraction involved.
How does the video handle equations with quadratic expressions?
-The video shows how to set the quadratic expression equal to zero and then solve for x using methods such as factorization or applying the quadratic formula.
What is the final form of the solution that the video demonstrates for a particularly tricky equation?
-The final form of the solution for the tricky equation is x = a + bβ13/b, where a and b are specific numerical values derived from the quadratic formula.
How does the video simplify the square root term in the quadratic formula?
-The video simplifies the square root term by factoring out common factors and using the properties of square roots to express the term in its simplest form.
What is the process for solving the last equation in the video?
-The process involves combining fractions over a common denominator, expanding and simplifying the numerator, multiplying both sides by the denominator to clear the fraction, and then solving the resulting quadratic equation.
What are the two solutions to the final equation presented in the video?
-The two solutions to the final equation are x = 8.5 and x = 1/3.
Outlines
π Introduction to Solving Algebraic Fraction Equations
This paragraph introduces the topic of solving equations involving algebraic fractions. It suggests reviewing a previous video on algebraic fraction operations and outlines the process of combining fractions on the left-hand side of an equation by finding a common denominator. The example given demonstrates converting fractions with denominators 6 and 4 into a common denominator of 12, combining them, and then solving the resulting equation to find x = 5.4.
π Expanding and Simplifying Equations with Algebraic Fractions
This section builds upon the initial approach by tackling a more complex equation with fractions having denominators of 6 and 9. The common denominator is determined to be 18, and the fractions are rewritten and combined accordingly. After expanding and simplifying the equation, the solution process involves multiplying both sides by 18 and isolating x to find x = 4.
π Solving Equations with Multi-term Denominators
The paragraph delves into solving equations where denominators have multiple terms, such as x + 2 and x + 5. The least common multiple of these is used as the common denominator, and the fractions are rewritten and combined. After expanding and simplifying, the equation is transformed into a quadratic equation. The process of solving this quadratic equation involves setting it to zero and factoring it to find two solutions, x = -4 and x = 1.
𧩠Advanced Quadratic Equations and Their Solutions
This part of the script addresses even more challenging equations with complex denominators. The equation is transformed into a quadratic form, and the quadratic formula is introduced as the method for solving it. The coefficients are identified, and the formula is applied to find the solutions in a specific form, a + bβ13/c. The final answer is simplified to match the form requested in the question.
π Final Challenge: Solving a Complex Fraction Equation
The final paragraph presents a complex equation with fractions on both sides. The common denominator is established, and the equation is simplified into a single fraction. After multiplying through by the denominators to clear the fractions, the resulting quadratic equation is solved by setting one side to zero and factoring. The solutions are found by setting each factor equal to zero, yielding x = 8.5 and x = 1/3.
Mindmap
Keywords
π‘Algebraic Fractions
π‘Common Denominator
π‘Lowest Common Multiple (LCM)
π‘Expanding Brackets
π‘Quadratic Equation
π‘Quadratic Formula
π‘Factorization
π‘Solving Equations
π‘Like Terms
π‘Completing the Square
π‘Difference of Squares
Highlights
Introduction to solving equations with algebraic fractions.
Building upon previous video on algebraic fractions operations.
Combining fractions with different denominators into one.
Finding the least common multiple (LCM) for denominators.
Rewriting fractions with a common denominator of 12.
Combining fractions over a common denominator to simplify equations.
Expanding brackets and collecting like terms to simplify equations.
Multiplying both sides by the denominator to clear fractions.
Solving a straightforward equation to find x = 27/5.
Approach to solving more complex equations with algebraic fractions.
Using the LCM of denominators 6 and 9, which is 18.
Combining fractions with a common denominator of 18.
Expanding and simplifying equations to solve for x.
Solving a quadratic equation by setting one side to zero.
Finding solutions to a quadratic equation using factorization.
Increasing difficulty with denominators that are binomial expressions.
Multiplying fractions with binomial denominators to find a common denominator.
Expanding and simplifying complex algebraic fractions.
Solving equations with quadratic results using the quadratic formula.
Using the quadratic formula to find solutions for x.
Simplifying square root expressions in the quadratic formula.
Final example with a complex equation requiring a common denominator approach.
Expanding and simplifying a complex equation with multiple terms.
Solving a quadratic equation with large coefficients.
Factorizing a quadratic equation to find possible solutions for x.
Finding two solutions for x by setting each factor equal to zero.
Conclusion and encouragement to try exam questions linked in the description.
Transcripts
[Music]
in this video we're going to learn how
to solve equations that have algebraic
fractions in them this video is going to
build upon a previous video the one
titled algebraic fractions operations
I'll put a link in this video's
description just in case you want to
check that one out
first so let's take an equation that has
some algebraic fractions in it what
we're going to do is focus on the left
hand side first of all and try and
combine these into one fraction to do
this we need to make sure we have a
common denominator at the moment the
denominators are 6 and four the lowest
common multiple of these is 12 so we
could rewrite the left hand side as two
fractions that are both over 12 if we
compare these two fractions here to get
from 6 to 12 on the bottom we must have
multiplied by two so we need to multiply
the top by two so that's 2 lots of x + 3
for the second fraction on the bottom to
get from 4 to 12 we've multiplied by
three so we multiply by three on the top
three lots of x + 1 and the right hand
side is still equal to
three now that we have the common
denominator we can combine these into
one big fraction all over 12 so we've
got two lots of x + 3 in between them we
have a plus sign and then three lots of
x + 1 and the right hand side is still
equals 3 next we need to expand the
brackets so I'm going to write the over2
and the equals 3 and then we're going to
expand the numerator here so we've got
two lots of x that's 2x two lots of
postive 3 that's POS 6 then we've got a
postive 3 * X that's POS 3x and then
pos3 * pos1 that's
pos3 we can now tidy up that numerator a
bit by collecting like terms so if we
write the over 12 and equals 3 we've got
2X and 3X that adds to make 5x and then
we've also got a six and a plus three
which gives you 9 we've now turned this
into a relatively straightforward equ
equation to solve we can multiply both
sides by 12 to get rid of that fraction
if you multiply by 12 on the left you
get 5x + 9 and if we multiply by 12 on
the right 3 * 12 is 36 then just
subtract 9 from both sides this will
give you 5x = 27 and then divide both
sides by 5 and this gives you x = 27 / 5
which is 5.4 so the solution to this
equation is
5.4 now let's try another example that's
a bit more tricky so for this one we're
going to use the same Approach at first
we're going to leave the right hand side
alone and try and combine the left hand
side into one big fraction looking at my
denominators this time of 6 and 9 the
lowest common multiple is 18 so I'm
going to write both of these as
something over 18 for the first fraction
to get from 6 to 18 we multiply by three
so we need to multiply X+ 2 on the top
by three as well so three lots of X+ 2
for the second fraction to get from 9 to
18 we multiply by two so we need two
lots of the top so two lots of x - 1 and
keep that right hand side the same equal
2/3 now we have that common denominator
we can combine them into one big
fraction all over 18 so we have three
lots of x + 2 then in between them a
subtraction sign and then two lots of x
- one and keep that right hand side the
same that's
2/3 then as we did before we're going to
expand those brackets so we'll write the
over 18 and the 2/3 down and then expand
these brackets we've got three lots of X
that's 3x three lots of pos2 that's plus
6 then we have -2 * X that's -2X and you
have to be really careful on this one
this is a really common mistake -2 * -1
is
positive2 then as before we'll collect
the like terms on the numerator so
everything else can be written down as
the same and then on the top we've got
3x - 2x that's just 1 x and then we've
got 6 + 2 which is 8 the next thing I
would do here is multiply both sides by
18 if we multiply by 18 on the left that
will cancel the 18 that's there so we
just have x + 8 and if you multiply the
right hand side by 18 we've got 2/3
multiplied by 18 that's just the same as
2/3 of 18 2/3 of 18 is 12 finally if we
subtract 8 from both sides we end up
with the answer x =
4 now let's increase the difficulty once
more and have a look at this question
here when we look at the denominators of
these fractions we can see they both
have two terms this means to find their
lowest common multiple we're going to
need to multiply them together so both
of these fractions can be Rewritten as
something over x + 2 x + 5 let's look at
the left fraction first so this one to
get from x + 2 to x + 2 * x + 5 we
obviously multiply by x + 5 so we need
to do this on the top as well so we need
four lots of x + 5 and then we can look
at the second fraction so to get from x
+ 5 to x + 2 * x + 5 we multiply by x +
2 so on the top we need to multiply by
x+2 as well and that's four lots of x+2
and of course the right hand side is
still just
two now that we have this common
denominator we can write them as one big
fraction all over x + 2 x + 5 so on the
numerators we have four lots of X+ 5
then in between them we have a plus sign
and then four lots of X+ 2 and the right
hand side is still equals 2 we can now
do some expanding and then simplifying
so if we expand out the numerator we've
got 4 * X which is 4X 4 * 5 which is +
20 4 * X which is 4X again and then 4 *
2 that's a positive
8 next we need to do the simplifying of
the numerator so on the top here we have
4x + 4x which is 8 x and then we also
have 20 + 8 which is
28 next we're going to multiply both
sides of this equation by both of those
brackets that are on that denominator so
by X+ 2 and x + 5 this will clear the
fraction on the left hand side to give
us 8x +
28 but on the the right hand side we'll
have two lots of x + 2 x + 5 next we'll
leave the left hand side alone and then
we've got two lots and then we'll expand
those brackets and whatever we get will
go inside this much larger bracket here
so if we expanded that double bracket
we'd have x * X that's x 2 we then have
x * 5 which is 5 x and 2 * X which is 2
X and 5 x and 2 x adds to make 7 x and
then finally we'd have 2 * 5 which is 10
on the right hand side we can then
expand this bra ET so if we leave the
left hand side alone on the right hand
side we have two lots of everything
that's in that bracket so two lots of
x^2 two lots of 7 x that's 14x two lot
of 10 that's 20 you can now see we have
a quadratic equation to solve when we
solve these we need to set one of the
sides equal to zero since the 2x^2 is on
the right hand side I'm going to make
the left hand side equal to zero to do
this I need to take away 8X and also
take away 28 from both sides if I took
away those from the left hand side I'd
get zero and if if I take those away
from the right hand side the 2x^2 will
remain unchanged but then I need to take
the 8X away from the 14x which is 6X and
then take the 28 away from the 20 which
is8 now there's a common factor of two
here to all terms so I can divide both
sides by two if I divide the left hand
side by two 0id by 2 is still 0o but
then on the right hand side 2x^2 ID 2 is
1 x^2 6X / 2 is 3x and8 ID 2 is -4
fortunately for us this quadratic will
factorize so on the left hand side we
have zero and the right hand side will
factorize to give x + 4 x -1 this leads
us to two solutions either the first
bracket is zero so x + 4 equal 0 in
which case X is -4 or the second bracket
equals 0 so X - 1 = 0 gives us the
solution X =
pos1 now let's have a look at an even
trickier question so for this one we
need to solve an equation but we've told
we need to give the answer in a
particular form
a plus orus < TK 13 / B this is a clear
indication that when we get to a
quadratic at the end it's not going to
factorize anymore we either need to use
the quadratic formula or complete the
square to get the solutions so let's go
ahead and try and solve this one so
first of all we'll look at those
denominators and we can see we've got x
+ 3 x - 3 so the product of those will
become our
denominators then we compare the first
fractions so to get from x + 3 to x + 3
x - 3 we multiply by x - 3 so we need to
multiply that six on the top by x - 3
and when we compare the second fractions
this time we've multiplied by x + 3 so
on the top we need two lots of x + 3 and
this equals 3 now we can combine them
into one big fraction over that common
denominator we have 6 lots of x - 3 in
between the fractions is a subtraction
sign and then 2 lots of x +
3 now we can expand out those brackets
so on the top we've got 6 * X that's 6 x
6 * -3
8 -2 * x -2X and a -2 * a POS 3 that's
A6 then we can collect those like terms
so on the top we've got 6X take 2x
that's 4X and then -8 subtract 6 that's
-4 then we would multiply both sides by
that denominator x + 3 x - 3 this will
clear the fraction on the left hand side
so you've just got 4x - 24 but on the
right hand side we have three lots of x
+ 3 x - 3 to solve this we'll leave the
left hand side alone and on the right
hand side we've got three lots of
whatever we get when we expand these two
brackets well this one's the difference
of two squares if we do x * X we get x2
and then we have x * -3 -3x but also
posi 3 * X which is postive 3x so those
X terms will cancel and then we have 3 *
3 which is 9 so we have 4x - 24 and then
if we expand this bracket three L of x^2
is 3x^2 and 3 lot of -9 is
-27 so you can see we do have a
quadratic and we need to get one of the
sides to be equal to zero once again I'm
going to make that the left hand side so
to make the left hand side equal to zero
I would need to subtract 4X and then add
24 to both sides so if I do that on the
left I get zero of course and on the
right hand side I get 3x^2 that remains
unchanged then I subtracted 4X and
there's no X term there already so
that's just -4x and then we need to add
24 to -27 which gives us -3 so we end up
with this quadratic equation here to
solve now remember we know from the form
they want the answer in we need to solve
this using the formula or completing the
square and this one's probably going to
be much easier using the quadratic
formula so we need to find the values of
a b and c they're the coefficients of X2
X and the constant term so the
coefficient of X2 is 3 the coefficient
of x is -4 and the constant term at the
end is -3 so a is 3 B is-4 and C is -3
now we can substitute those values into
the quadratic formula it's x equal
negative B well B is already negative so
if we did negative B it will become
positive so it's actually a positive 4
plus or minus the square root of then
b^2 so -4 2 subtract four lots of a
which is 3 multipli C which is -3 and
all of this is divided by two lots of a
a and 2 lot of a is 2 lots of three so
six now this question would actually be
a non-calculator question so we're going
to need to work out the value of the
number that's inside that square root so
let's write x = 4 plus or minus the < TK
of over 6 but we'll work out what's
inside that square root so if we did -4
squar that would be -4 multiplied by
itself so
16 and then if we did4 multipli by 3
that's -12 and then multiply that by -3
that becomes a positive
36 so we end up with 16 + 36 inside that
square root you can add those two
together that's 52 so x = 4 plus or- <
TK 52 / 6 next what we need to do is
simplify that < TK 52 so using our third
rules if we take root 52 that could be
expressed Asun 4 multiplied
byun3 the square < TK 4 is just two so
this is 2 < tk13 so in place ofun 52 we
could write 2K3 so it's X = 4 plus orus
2un 13 now over 6 now this is looking a
lot like the answer but we're still not
quite there that one just has 1 < TK 13
and we have two the reason for that is
we have a common factor of two here if
we divide all terms by two we get x
equals if we divide the four by two we
get two divide 2 < tk3 by two you get
1un 13 and divide 6 by two you get three
this answer now matches the form we were
asked in the question you can see the
value of a is 2 2 and the value of B is
three now we're going to look at one
more final question this one here we're
going to start this one how we started
all of the previous questions we're
going to write the left hand side over a
common denominator so for this one it'll
be the product of x + 17 and 2x -
5 so if we compare these first two
fractions you can see we've multiplied
by 2x - 5 so if we multiply by 2x - 5 on
the top we get 3 x lots of 2x -
5 and and for the right fractions when
we compare these we've multiplied by x +
17 so we need three lots of x + 17 and
the right hand side is equal to 3 over
4 now we have that common denominator we
can write them as one big fraction so
we've got 3x and then brackets 2x - 5
then we have a subtraction in between
them and 3x +
17 next we're going to expand out that
numerator so we'll write everything else
the same we have 3x * 2x that's 6 x^2 3x
* -5 that's
15x -3 * X -3x and -3 * pos7 is
-51 now there's a little bit of
simplifying we can do on the numerator
so we can't simplify the 6x2 that's the
only term of x^2 but we can simplify -5x
subtract 3x which is -8x and then
subtract
51 so now we've written the left hand
side as a single fraction what we're
going to do next is multiply both sides
by both of those brackets on that
denominator so if we multiply the left
hand side by x + 17 and 2x - 5 that will
clear the fraction so we've got 6x^2 -
18x - 51 and on the right hand side
we've just multiplied this
3/4 by both of those brackets now in the
previous couple of questions we haven't
had to deal with a fraction like this on
the right hand side it was just an
integer before those two brackets to
deal with this fraction you can just
multiply both sides by four if we
multiply the left hand side by four we
get four lots of the left hand side and
if we multiply the right hand side by
four that four will cancel so we've just
got three lots of those two
brackets now we've got lots of expanding
to do so on the left hand side we need
to multiply by four so we've got four
lots of 6x^2 that's 24 x^2 four lots of
-8x that's - 72x and four Lots of- 51 is
-24 then on the right hand side we're
going to write a three and then a big
bracket then expand out the double
bracket and write the terms inside this
big bracket ET so we've got x * 2x first
that's
2x^2 then we would do x * -5 so -5x but
we would also do 17 * 2x which is a
positive
34x so we've got - 5x + 34x that's
positive
29x and finally 17 * -5 is
85 we can leave that left hand side
alone and expand this bracket on the
right hand side we need to multiply by
three this time 3 lots of 2x^2 is 6x^2 3
lots of 29x is 87x and 3 lots of 85 is -
255 so we do end up with a quadratic
equation to solve since we have more X
squs on the left hand side I'm going to
make the right hand side equal to zero
on this one so i' need to subtract 6x^2
subtract 87x and add 255 to both sides
so on the left hand side if I subtract 6
x^2 from 24 x^2 I get 18 x^2 and then if
I subtract 87x from the 72x we get
159x and then if we add 255 to ne24 we
end up with a positive 51 and the right
hand side we know will equal
zero now let's take that quadratic
equation and we're going to solve it
this one does look really nasty because
of the size of the numbers but there is
actually a common factor of three here
if you divide 18 x^2 by 3 you get 6 x^2
divide -9x by 3 that's - 53x and divide
the 51 by 3 that's 17 and of course if
you divide 0 by three that's still zero
so we're going to factorize this one
actually it will factorize into two
brackets now it's actually quite
fortunate we have a 17 at the end since
we have a 17 that's a prime number we
know its factors are only 1 and 17 so if
it did factorize the only possible
numbers we could put at the end of these
brackets would be 1 and 17 and they
would actually both be negative as well
since a negative times a negative gives
you a positive so we still get a
positive 17 but the only way we'd end up
with a 53x is if we had negative terms
here if they were both positive that 53x
wouldn't be attainable so we can put 17
and Ne -1 in these brackets and then we
just need to think about a few of the
different combinations to try and get
that 6x^ s so we're either going to use
a 6X and a 1x or a 3X and a 2x now if
you try a few different combinations out
it shouldn't take you too long to
realize we need 2x - 17 and 3x - 1 if
you won't give this a go and expand it
out and you'll see it does give that
quadratic a b
so finally to get our two solutions we
need to set the first bracket equal to 0
so 2x - 17 = 0 or the second bracket
equal to 0 so 3x - 1 = 0 to solve the
left one you can add 17 to both sides
and get 2x = 17 and then divide both
sides by two to get x = 8.5 for the
right one you can add one to both sides
so 3x = 1 and divide both sides by 3 to
get x =
1/3 thank you for watching this video I
hope you found a useful check out the
one I think you should watch next
subscribe so you don't miss out on my
future videos and now go ahead and try
the exam questions I've Linked In this
video's
description
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