(y-3)×(y-3)×(y-3)×(y-3)等于多少
问题描述：
(y-3)×(y-3)×(y-3)×(y-3)等于多少
答
(y - 3)(y - 3)(y - 3)(y - 3)
= (y^2 - 6y + 9)^2
= y^4 + 2y^2( - 6y + 9) + ( - 6y + 9)^2
= y^4 - 12y^3 + 18y^2 + 36y^2 - 108y + 81
= y^4 - 12y^3 + 54y^2 - 108y + 81
另外（a + b)^4
= a^4 + 4 a^3 b + 6 a^2 b^2 + 4 a b^3 + b^4
令 a = y,b = -3,代入后依然可以得到
(y - 3)^4 =y^4 - 12y^3 + 54y^2 - 108y + 81