(x+3)*(x2+9)*(x-3)=?
问题描述:
(x+3)*(x2+9)*(x-3)=?
答
利用平方差公式得
(x+3)*(x^2+9)*(x-3)
=(x+3)*(x-3)*(x^2+9)
=(x^2-9)(x^2+9)
=x^4-81