x³+2x²-5x-6=0

题目

x³+2x²-5x-6=0

答案

(x^3 + x^2) + (x^2 - 5x - 6) = x^2*(x+1) + (x+1)(x-6) = (x+1)(x^2 + x-6) (x+1)(x+3)(x-2) = 0
所以,它的解有：x = -1,x = -3,x = 2