把下列各式分解因式 (x+y)^2-(2x-y)^2 9(2x-y)^2-4(x+2y)^2 (m-1)^2-64 (a

(x+y)^2-(2x-y)^2
=（x+y+2x-y）（x+y-2x+y）
=3x(2y-x)
9(2x-y)^2-4(x+2y)^2
=[3(2x-y)+2(x+2y)][3(2x-y)-2(x+2y)]
=(8x+y)(4x-7y)
(m-1)^2-64
=(m-1+8)(m-1-8)
=(m+7)(m-9)
(am+bm+c)^2-(am+bm-c)^2
=(am+bm+c+am+bm-c)(am+bm+c-am-bm+c)
=2(am+bm)*2c
=4mc(a+b)
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