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Mathematics 8 Online
OpenStudy (anonymous):

Help please! Solve for x

OpenStudy (anonymous):

OpenStudy (unklerhaukus):

can you factor the denominator of the first term?

OpenStudy (unklerhaukus):

like this\[x^2-2x+1 = (x-\dots)(x-\dots)\]

OpenStudy (anonymous):

no...

OpenStudy (unklerhaukus):

then ...'s have to multiply to give +1, and add to give -2

OpenStudy (anonymous):

Do you mean that I have to add and subtract numbers from both sides so I can cancel them out?

OpenStudy (unklerhaukus):

not yet, we have to factor the denominators first

OpenStudy (unklerhaukus):

what are the factors of 1?

OpenStudy (anonymous):

1

OpenStudy (unklerhaukus):

right, now we and multiply in the two ...'s together to get +1 so we could have +1 x +1 = +1, or -1 x -1 = +1

OpenStudy (unklerhaukus):

if we add -1 and -1 we get -2 which is what we want.

OpenStudy (unklerhaukus):

We get: \[x^2-2x+1 = (x-1)(x-1)\]

OpenStudy (anonymous):

We want -2 so we can get rid of -2x, right?

OpenStudy (unklerhaukus):

yeah. If we expand it back out \[(x-1)(x-1) = x(x-1)-1(x-1)\\ \qquad\qquad\qquad=x^2-x-x+1\\ \qquad\qquad\qquad=x^2-2x+1\\ \] so we know we have factored correctly

OpenStudy (unklerhaukus):

Now we want to factor the denominator of the second term, something like this \[1-x^2 = (\dots)(\dots)\]

OpenStudy (unklerhaukus):

this is a difference of squares

OpenStudy (unklerhaukus):

\[a^2-b^2 = (a-b)(a+b)\] if you expand it back out , you can check the middle term cancels away

OpenStudy (unklerhaukus):

Can you factor \[1-x^2 = \]

OpenStudy (anonymous):

(−x+1)(x+1)

OpenStudy (unklerhaukus):

cool,

OpenStudy (unklerhaukus):

so you have \[\begin{align} \frac{3}{x^2-2x+1}+\frac2{1-x^2} &=\frac1{1+x}\\ \frac{3}{(x-1)(x-1)}+\frac2{(-x+1)(x+1)} &=\frac1{1+x}\\ \frac{3}{(x-1)(x-1)}-\frac2{(x-1)(x+1)} &=\frac1{1+x}\\ \end{align}\] right?

OpenStudy (anonymous):

Right.

OpenStudy (unklerhaukus):

Now, we want to get rid of all those denominators by multiplying. multiply both sides of the equation by \((x-1)(x-1)(x+1)\) (but don't expand any brackets)

OpenStudy (anonymous):

3 - 2/x-1 = I have trouble with the right side....

OpenStudy (unklerhaukus):

\[\begin{align} \frac{3}{(x-1)(x-1)}+\frac2{(x-1)(x+1)} &=\frac1{1+x}\\[2ex] \frac{3(x−1)(x−1)(x+1) }{(x-1)(x-1)}-\frac{2(x−1)(x−1)(x+1) }{(x-1)(x+1)} &=\frac{(x−1)(x−1)(x+1) }{x+1}\\[2ex] \frac{3\cancel{(x−1)(x−1)}(x+1)}{\cancel{(x-1)(x-1)}}-\frac{2(x−1)\cancel{(x−1)(x+1)}}{\cancel{(x-1)(x+1)}} &=\frac{(x−1)(x−1)\cancel{(x+1)}}{\cancel{x+1}}\\[2ex] 3(x+1)-2(x-1)&=(x-1)(x-1) \end{align}\]

OpenStudy (anonymous):

Ohhhh....right XD

OpenStudy (unklerhaukus):

now i guess you can expand the brackets and solve from here

OpenStudy (unklerhaukus):

what do you get when you expand?

OpenStudy (anonymous):

yep! That's all I need help with! Thanks a bunch!! (sorry for the late reply)

OpenStudy (anonymous):

@UnkleRhaukus

OpenStudy (anonymous):

do you need help

OpenStudy (qwertty123):

@LYRA_Z you still need help?

OpenStudy (anonymous):

Nope, not anymore, thanks!

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