计算：4(x+2y)²-9(x-y)²
问题描述：
计算：4(x+2y)²-9(x-y)²
答
4(x+2y)²-9(x-y)²
=[2(x+2y)+3(x-y)][2(x+2y)-3(x-y)]
=(5x+y)(7y-x)
答
4(x+2y)²-9(x-y)²
=[2(x+2y)]²-[3(x-y)]²
=(2x+4y-3x+3y)(2x+4y+3x-3y)
=(7y-x)(5x+y)