Un-Simplifying a fraction, i.e. computing partial fraction decomposition $\frac{3x^2+17x}{x^3+3x^2+-6x-8}$
I need to find the value of C in the form of 
$\frac{A}{x+1} + \frac{B}{x-2} + \frac{C}{x+4}$
which is based on the fraction give at the top.
I can get so far to do the following:
$A(x^2+2x-8) + B(x^2+5x+4) + C(x^2-x-2) = 3x^2+17x$
No clue on my next step or even if this is the right step.

Compare coefficients of both sides polynomials. for example by comparing coefficient next you $x^2$ you will get $A+B+C = 3$. Do the same for $x^1$ and $x^0$ and solve system of 3 linear equations.
The other way is to put arbitrary 3 values of $x$, for example $-1$, $0$ and $1$, and again you will get system of 3 linear aquations with variables $A$, $B$ and $C$.
