a-b=3,ab=2,求a²+b²
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a-b=3,ab=2,求a²+b²
a-b=3,ab=2,求a²+b²
a-b=3,ab=2,求a²+b²
5
a^2+b^2=(a-b)^2+2ab=3^2+2*2=13
a-b=3,ab=2,
a²+b²
=(a-b)²-4ab
=3²-4×2
=9-8
=1
根据题意:
(a-b)² = 9
于是:
a²-2ab+b² = 9
因此:
a²+b² = 9+2ab = 9 + 4 = 13