Question

先化简再求值2(x的平方y+xy)-3(x的平方y+4x的平方y)-4x的平方y,其中x=-2,y=1/2

Answer 1

解：2(x^2y+xy)-3(x^2y+4x^2y)-4x^2y
=2x^2y+2xy-3x^2y-12x^2y-4x^2y
=-17x^2y+2xy
把团伏x=-2,y=1/2代入得：原塌高携式=-17(-2)^2*2*(1/2)+2*(-2)*(1/念仔2)=-36