2a平方+2b平方+3>2ab+2a-2b
问题描述:
2a平方+2b平方+3>2ab+2a-2b
答
2a²+2b²+3-2ab-2a+2b
=a²-2ab+b²+a²-2a+1+b²+2b+1+1
=(a-b)²+(a-1)²+(b+1)²+1
≥1>0
∴2a²+2b²+3>2ab+2a-2b