我接着上面两楼的吧f（x）=x³-3x²+4 = x³-2x²-x²+4 = x²(x-2) + (4-x²) = x²(x-2) + (2-x)(2+x) = (x²-x-2)(x-2) = (x+1)(x-2)(x-2)>0当x不等于2的时候,（x-2)的平方...