(1)比较x2-x与x-2的大小(x∈R)
(2)比较(a+3)(a-5)与(a+2)(a-4)的大小(a∈R)
网友回答
解:(1)∵x2-x-(x-2)=x2-2x+2=(x-1)2+1>0,
∴x2-x>x-2;
(2)∵(a+3)(a-5)-(a+2)(a-4)
=a2-2a-15-(a2-2a-8)
=-7<0,
∴(a+3)(a-5)<(a+2)(a-4).
解析分析:(1)将x2-x与x-2作差即可;(2)将(a+3)(a-5)与(a+2)(a-4)作差即可.
点评:本题考查不等式比较大小,突出考查不等式比较大小的基本方法“作差法”,属于基础题.