# Math Help - comparing coefficients

1. ## comparing coefficients

Ok just quickly what happens in this case

A + B = 3
-2A - 2B = -2

Both terms disapear when I add them together.. what do i need to do to get the values of A and B??

2A +2B = 6
-2A -2B = -2

0 = 4

2. What was the original question?

Divide the second equation by -2 and we have: \begin{aligned} A + B & = 3 \\ A + B & = 1 \end{aligned}

3. I see...

I was doing partial fractions,

int (3-2x) / (x^2-4x+4)

int (3-2x) / (x-2)(x-2)

A(x-2)+B(x-2)

Numerator: (A+B)x + (-2A-2B)

I'm guessing I've done something wrong here..

4. You have to combine the linear factors in the denominator into a single power: $\int \frac{3-2x}{x^2 - 4x + 4} \ dx = \int \frac{3-2x}{(x-2)^2} \ dx$

Then apply partial fraction decomposition: $\frac{3 - 2x}{(x-2)^2} = \frac{A}{x-2} + \frac{B}{(x-2)^2}$

Try it now.

5. Ah right I get it, thanks alot!!