Question

How to solve this?`f=(2x^2-x-1)^10`Calculate `x_1+x_2+x_3+...+x_20`.

Answer 1

`5`

Explanation:

`2x^2-x-1 =2 (x+1/2)(x-1)` and

`(2x^2-x-1)^10=2^10(x+1/2)^10(x-1)^10` so the sum of their `20` roots is `x_1+x_2+cdots+x_20 = 10 xx 1-10 xx 1/2 = 5`