(3x+2y)²-(x+2y)²
=[(3x+2y)-(x+2y)][(3x+2y)+(x+2y)]
=2x(4x+4y)
=8x(x+y)
明白请采纳,
有新问题请求助,我就这么写扣了1分可能老师心情不好！