(x+3)(x-4)(x+5) is identical to x^3 +ax^2 -17x+b. Find the value of a and the value of b.

Multiplying out the first two brackets gives (x^2-x-12)(x+5). Multiplying the remaining brackets gives x^3 + 4x^2 -17x - 60.

a = 4b = 60