Question

find the coefficient of x^7 in the expansion of (x-1/x^2)^40

Answer 1

Answer:

by binomial expansion

40c0x^40 + 40c1x^39(1/x^2).........40c11x^29(1/x^2)^11 ......40c40x^0(1/x^2)^40

40c11x^29(1/x^2)^11 this is the coefficient of x^7 in the expansion of                  (x-1/x^2)^40

2,311,801,440 is the coefficient of x^7 in the expansion of (x-1/x^2)^40