Question

函数f(x)=x的三次方-2x的平方-x+2的零点的个数是?

Answer 1

f(x）=x^3-2x^2-x+2=x^2(x-2)-(x-2)=(x-2)(x^2-1)=(x-2)(x-1)(x+1)

零点为x=2,1,-1.共3个.