Compute the coefficientsof x^5 in (1+2x+3x^2)(3+2x+x^2)(1+x+x^2).
A.11
B.9
C.8
D.5
x^5 terms can only arise from the following combinations:
2x*x^2*x^2 coeff → 2
3x^2*2x*x^2 coeff → 6
3x^2*x^2*x coeff → 3
So overall coefficient of x^5 tterm is 2 + 6 + 3 → 11 (solution A in your list).
