Question

若a²+b²=3，a-b=1.2,求ab的值

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Answer 1

a²+b²=3
(a-b)²+2ab=3
1.44+2ab=3
2ab=1.56
ab=0.78

Answer 2

解：a-b=1.2, ∴（a-b）^2=1.44,即a^2+b^2-2ab=1.44 ∵a²+b²=3
∴ab=0.78

Answer 3

0.78