一道高一数学因式分解题

来源:百度知道 编辑:UC知道 时间:2024/03/29 23:14:22
(x+1)(x+3)(x+5)(x+7)-9
如果好的话,还可追加分

(X+1)(X+3)(X+5)(X+7)-9
=(x+1)(x+7)(x+3)(x+5)-9
=(x^2+8x+7)(x^2+8x+15)-9
令x^2+8x+7=t
(X+1)(X+3)(X+5)(X+7)-9
=(x^2+8x+7)(x^2+8x+15)-9
=t(t+8)-9=t^2+8t-9=(t+9)(t-1)
=(x^2+8x+7+9)(x^2+8x+7-1)
=(x^2+8x+16)(x^2+8x+6)
=(x+4)^2*(x^2+8x+16)

不懂发消息问我

设取四个式的平均值X+4=t 代入
=(t-3)(t-1)(t+1)(t+3)-9
=(t^2-9)(t^2-1)-9
=t^4-10t^2
=......