因式分解：-0.25(x+y)^2+0.81(x-y)^2_数学解答

因式分解：-0.25(x+y)^2+0.81(x-y)^2

人气：333 ℃　时间：2020-03-26 04:52:04

解答

-0.25(x+y)^2+0.81(x-y)^2
=[0.9(x-y)+0.5(x+y)][0.9(x-y)-0.5(x+y)]
=(1.4x-0.4y)(0.4x-1.4y)
=0.04(7x-2y)(2x-7y)