问题描述:
(x平方+7x+10)/(x平方+6x+5) × (x三次方+1)/(x平方+4x+4) ÷ (x平方-x+1)/x-2 其中,x=4.
问题解答:
我来补答
(x²+7x+10)/(x²+6x+5) × (x³+1)/(x²+4x+4) ÷ (x²-x+1)/(x-2)
=(x+2)(x+5)/(x+5)(x+1) × (x³+1)/(x+2)² ÷ (x²-x+1)/(x-2)
=(x+2)/(x+1) × (x³+1)/(x+2)² ÷ (x²-x+1)/(x-2)
=(x+2)/(x+1) × (x³+1)/(x+2)² ×(x-2) / (x²-x+1)
=1/(x+1) × (x³+1)/(x+2) ×(x-2) / (x²-x+1)
=1/(x+1) × (x+1)(x²-x+1)/(x+2) ×(x-2) / (x²-x+1)
=1/(x+1) × (x+1)/(x+2) ×(x-2)
=1/(x+2) ×(x-2)
=(x-2)/(x+2)
=(4-2)/(4+2)
=2/6
=1/3
再问: x³+1怎么=(x+1)(x²-x+1)的?不明白啊
再答: a³+b³=(a+b)(a²-ab+b²)