(X^2-4X-12)(X^2-4X+3)+56
问题描述:
(X^2-4X-12)(X^2-4X+3)+56
9倍怎么来的
答
(X^2-4X-12)(X^2-4X+3)+56
=(x²-4x)²-9(x²-4x)+20
=(x²-4x-5)(x²-4x-4)
=(x-5)(x+1)(x²-4x-4)