(x+3)(x-4)-x(x-2),化简求值,其中x=12.5

问题描述:

(x+3)(x-4)-x(x-2),化简求值,其中x=12.5

(x+3)(x-4)-x(x-2)=x²-x-12-x²+2x=x-12=12.5-12=0.5