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比较两个代数式的大小:当x>1时,x三次方与x²-x+1
人气:399 ℃ 时间:2020-06-27 06:05:14
解答
x³-(x²-x+1)
=x³-x²+x-1
=x²(x-1)+(x-1)
=(x²+1)(x-1)
x²+1恒>0
x>1 x-1>0
(x²+1)(x-1)>0
x³-(x²-x+1)>0
x³>x²-x+1
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