化简求值:[2x²-(x+y)(x-y)][(2-x)(x+2)+(-y-2)(2-y)]其中x=-1,y=½
问题描述:
化简求值:[2x²-(x+y)(x-y)][(2-x)(x+2)+(-y-2)(2-y)]其中x=-1,y=½
答
原式=(2x²-x²+y²)(4-x²+y²-4)
=(x²+y²)(y²-x²)
=y^4-x^4
=1/16-1
=-15/16