当x=2,(x-x²-5)-(2x²+7x-3)等于几

问题描述:

当x=2,(x-x²-5)-(2x²+7x-3)等于几

-26

当x=2,
(x-x²-5)-(2x²+7x-3)=x-x²-5-2x²-7x+3=-x²-6x-2=-2²-6×2-2=-4-12-2=-18