Question

Given that f(a) = a (a + 1) (a + 2) where a = 1, 2, 3, . Then find s = f(1) + f(2) + f(3) + + f(10)?

Answer 1

Answer:

f(a)=a^3+3a^2+2a

s=sigma a=1 to 10 f(a)

sigma a^3=n^2(n+1)^2/4

sigma a^2=n(n+1)(2n+1)/6

sigma a=n(n+1)/2

so answer is 4290