化简 求值 x-{-5x-[-y+(-x+3y)+x]},其中x=-1,y=-2;
问题描述:
化简 求值 x-{-5x-[-y+(-x+3y)+x]},其中x=-1,y=-2;
答
x-{-5x-[-y+(-x+3y)+x]},
=x+5x+[-y+(-x+3y)-x]
=6x-y+(-x+3y)-x
=5x-y-x+3y
=4x+2y
=4×(-1)+2×(-2)
=-4-4
=-8