已知x-y=3,求代数式(x+y)(x-y)+(x-y)²-(2xy-2y)²的值
问题描述:
已知x-y=3,求代数式(x+y)(x-y)+(x-y)²-(2xy-2y)²的值
答
﹙x-y﹚﹙x+y+x-y-2y﹚=2﹙x-y﹚﹙x-y﹚=2×3×3=18
已知x-y=3,求代数式(x+y)(x-y)+(x-y)²-(2xy-2y)²的值
﹙x-y﹚﹙x+y+x-y-2y﹚=2﹙x-y﹚﹙x-y﹚=2×3×3=18