杭州交通信息网蓬莱仙洞农家住宿:初一数学
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分解因式:(x+1)(x+2)(x+3)-6*7*8=_____________
(x+1)(x+2)(x+3)-6*7*8
设A=x+2
(A-1)A(A+1)-6*7*8
=(A^3-A)-(7^3-7)
=(A^3-7^3)-(A-7)
=(A-7)(A^2+7A+49-1)
=(x-5)[(x+2)^2+7(x+2)+48]
=(x-5)(x^2+11x+66)
分解因式:(x+1)(x+2)(x+3)-6*7*8=____________
设x+2=K
（K-1）K（K+1）-6*7*8
=(K^3-K)-(7^3-7)
==(K^3-7^3)-(K-7)
=(K-7)(K^2+7K+49-1)
=(X-5)[(x+2)^2+7(x+2)+48]
=(X-5)(x^2+11x+66)