x(x-1)(x+3)-x(x-20)^2+7x+1,其中2=1/2

问题描述:

x(x-1)(x+3)-x(x-20)^2+7x+1,其中2=1/2

是不是x=1/2呀?x(x-1)(x+3)-x(x-20)^2+7x+1=(1/2)(-1/2)(7/2)-(1/2)[(-39/2)^2]+7(1/2)+1=-7/8-1521/8+36/8=-1492/8=-373/2