From the question you can find that the roots of the equation will be 1,2,3,...50 Coefficient of x^49 is a1. You can use a trick here, consider(x-a)(x-b)= x^2- (a+b)x +b^2 Similarly x^50-(1+2+3+4+.....49)x^49+....... will be the expansion. The coefficient of x^49 will be sum of 1 to 49
Anju, thanks for your reply. But can you explain steps in more detail .l fear l hadn't got your method.
The expansion will be x^50 +a1x^49+a2x^48+......+a49x+a50 =0 The roots of the equation are 1,2,3,4....50 a1 is the minus of the sum of roots of the equation. a1=-(1+2+3+...50) =-1275