Finding Unknown Coefficients of X (Another Problem)

For all x, find the values of the constants a and b in:

$\displaystyle \displaystyle (x+a)(x^2+bx+2)=x^3+2x^2-5x-6$

Multiplied out i get:

$\displaystyle \displaystyle x^3+bx^2+2x+ax^2+abx+2a=x^3+2x^2-5x-6$

I then move the 2x over to the other side of the equation and cancel the cubed x's giving me:

$\displaystyle \displaystyle bx^2+ax^2+2a=-4x^2-x-6$

Then i'm stuck as i have two seperate variables attatched to a like power of x :?

Any help would be great!