若A=a2+5b2-4ab+2b+100，求A的最小值．
人气：359 ℃ 时间：2019-10-24 14:24:08
解答
A=a2-4ab+4b2+b2+2b++1+99
=（a-2b）2+（b+1）2+99，
∵（a-2b）2≥0，（b+1）2≥0，
∴A≥99，
∴A的最小值为99．
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