因式分解,9(x-y)²-y²,9a²-4(b+c)²,(x+y+z)²-(x-y-z)²,
问题描述:
因式分解,9(x-y)²-y²,9a²-4(b+c)²,(x+y+z)²-(x-y-z)²,
答
9(x-y)²-y²,=[3(x-y)]²-y²=[3(x-y)+y][3(x-y)-y]=(3x-2y)(3x-4y)9a²-4(b+c)²,=(3a)²-[2(b+c)]²=[3a+2(b+c)][3a-2(b+c)]=(3a+2b+2c)(3a-2b-2c)(x+y+z)²-(x-y-z)...