已知（a+b）²=17,ab=3.求（a-b)²的值

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已知（a+b）²=17,ab=3.求（a-b)²的值
已知（a+b）²=17,ab=3.求（a-b)²的值

已知（a+b）²=17,ab=3.求（a-b)²的值
解
(a-b)²
=(a+b)²-4ab
=17-4×3
=17-12
=5