计算.25(x+y)^2-0.81(x-y)^2
问题描述：
计算.25(x+y)^2-0.81(x-y)^2
0.25(x+y)^2-0.81(x-y)^2 .
答
分解因式
0.25(x+y)^2-0.81(x-y)^2
=[0.5（x+y)+0.9(x-y)][0.5（x+y)-0.9(x-y)]
=(1.4x-0.4y)(0.4x+1.4y)题目错了...0.25(x+y)^2-0.81(x-y)^2抱歉分解因式0.25(x+y)^2-0.81(x-y)^2=[0.5（x+y)+0.9(x-y)][0.5（x+y)-0.9(x-y)]=(1.4x-0.4y)(0.4x+1.4y)