4(3x+2y)的2次方—9(x—y)的2次方
问题描述:
4(3x+2y)的2次方—9(x—y)的2次方
答
=[2(3x+2y)]²-[3(x-y)]²
=(6x+4y+3x-3y)(6x+4y-3x+3y)
=(9x+y)(3x+7y)