my prof did this in his lecture:
$\displaystyle \frac{A(x-1)+B(x+2)}{(x+2)(x-1)}$
= $\displaystyle \frac{x(A+B)+2(A-B)}{(x+2)(x-1)}$
Can anyone tell me what he did?
Hi again
$\displaystyle =\frac{Ax-A+Bx+2B}{(x+2)(x-1)}$, by expanding.
$\displaystyle =\frac{Ax+Bx-A+2B}{(x+2)(x-1)}$, by rearranging.
There's something wrong in what you've written ~= $\displaystyle \frac{x(A+B)+({\color{red}2B-A})}{(x+2)(x-1)}$
Can anyone tell me what he did?