long division help

Original post by Mr Tall

How do I do

\frac{2x^2 - 4x -1}{x(x-1)}

I know I do long division but I can't do it with this one? And I also know we expand out the bottom brackets! Whats the catch with this question?

many thanks!

I am not sure what you are asking

You can do long division with the expanded denominator

Or you could do partial fractions

Reply 2

Original post by TenOfThem

I am not sure what you are asking

You can do long division with the expanded denominator

Or you could do partial fractions

is this a difficult division question for C3 if you were to do it by long division?

I would show my working out but I can't on this.. but basically I can't do the long division for it

would it be easier to do by partial fractions?

Reply 3

Original post by Mr Tall

I would use partial fractions as a personal preference but the long division is very straightforward

Reply 4

Original post by TenOfThem

I would use partial fractions as a personal preference but the long division is very straightforward

eugghhh

I'm making a silly error some where then in my long division but I can't figure it out!! :frown:

I can't even post a picture on here of my workings as my phone got stolen!

Reply 5

Original post by TenOfThem

I would use partial fractions as a personal preference but the long division is very straightforward

do I not have to divide as I have an X^2 term on both the numerator and denominator ?

Reply 6

Original post by Mr Tall

do I not have to divide as I have an X^2 term on both the numerator and denominator ?

no, why would that mean that you have to divide

\dfrac{2x^2-4x-1}{x^2-x} = 2 + \dfrac{A}{x} + \dfrac{B}{x-1}

(edited 10 years ago)

Reply 7

Original post by TenOfThem

I would use partial fractions as a personal preference but the long division is very straightforward

whats going on here:

\frac{2x^2+5}{(x-4)(x+2)} = \frac{2x^2 +5}{x^2 -2x + 8}

\frac{2(x^2 -2x -8) + 4x + 21}{x^2 -2x -8}

2 + \frac{4x+21}{x^2 - 2x - 8}

Reply 8

Original post by Mr Tall

whats going on here:

\frac{2x^2+5}{(x-4)(x+2)} = \frac{2x^2 +5}{x^2 -2x + 8}

\frac{2(x^2 -2x -8) + 4x + 21}{x^2 -2x -8}

2 + \frac{4x+21}{x^2 - 2x - 8}

That is a method of doing long division where you just adjust the numerator

Reply 9

\frac{2x^2 - 4x -1}{x(x-1)}

write as partial fractions

ok so I do

\frac{2(x^2-x)-2x-1}{x^2-x}

to get

2-\frac{2x-1}{x^2-x}

then I get A(X-1) + BX= 2X^2 -4X -1 then when I solve i get B=-3 and A=5

giving me 2-\frac{5}{x}-\frac{3}{x+1}

which is wrong according to my text book! What have a done wrong? thanks

Reply 10

\frac{2x^2 - 4x -1}{x(x-1)}

write as partial fractions

ok so I do

\frac{2(x^2-x)-2x-1}{x^2-x}

to get

2-\frac{2x-1}{x^2-x}

then I get A(X-1) + BX= 2X^2 -4X -1 then when I solve i get B=-3 and A=5

giving me

2-\frac{5}{x}-\frac{3}{x+1}

which is wrong according to my text book! What have a done wrong? thanks

Reply 11

Original post by Mr Tall

\frac{2x^2 - 4x -1}{x(x-1)}

write as partial fractions

ok so I do

\frac{2(x^2-x)-2x-1}{x^2-x}

to get

2-\frac{2x-1}{x^2-x}

then I get A(X-1) + BX= 2X^2 -4X -1 then when I solve i get B=-3 and A=5

giving me 2-\frac{5}{x}-\frac{3}{x+1}

which is wrong according to my text book! What have a done wrong? thanks

It should be 2x+1 as the numerator of your fraction once you have divided.

Reply 12

Original post by Mr M

It should be 2x+1 as the numerator of your fraction once you have divided.

how?

Reply 13

Original post by Mr Tall

how?

How? Subtraction of a negative number ...

Reply 14

Original post by Mr M

How? Subtraction of a negative number ...

oh, silly me! :colondollar:

thanks

x^3 + 3x^2 -3x -11 divided by x^2 + 3x -4... i can't do this! When I do the long division for it!! i cant even post my working because I dont have a camera.... is there a trick in that division question?? Im really stuck! PLease help my mock is in 2 days and I'm going to fail :frown:

Reply 15

Original post by Mr Tall

oh, silly me! :colondollar:

thanks

Why don't you use the method you tried before?

x(x^2+3x-4)+Ax+B=x^3+3x^2-3x-11

Reply 16

Original post by Mr M

Why don't you use the method you tried before?

x(x^2+3x-4)+Ax+B=x^3+3x^2-3x-11

I can do it by that method, but I can't do it by the long division method! It's really frustrating I just want to be able to do it by long division... Is there a catch in it somewhere that I'm missing?

Reply 17

krisshP

Original post by Mr Tall

oh, silly me! :colondollar:

thanks

Reply 18