因式分解 x*+10*+21-4y*-8y
问题描述:
因式分解 x*+10*+21-4y*-8y
答
x²+10x+21-4y²-8y
=x²+10x+25-4y²-8y-4
=(x+5)²-4(y+1)²
=[(x+5)+2(y+1)][(x+5)-2(y+1)]
=(x+2y+7)(x-2y+3)