已知(a-b)=5,ab=3,求(a+b)^2与3(a^2+b^2)的值.

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已知(a-b)=5,ab=3,求(a+b)^2与3(a^2+b^2)的值.
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已知(a-b)=5,ab=3,求(a+b)^2与3(a^2+b^2)的值.
已知(a-b)=5,ab=3,求(a+b)^2与3(a^2+b^2)的值.

已知(a-b)=5,ab=3,求(a+b)^2与3(a^2+b^2)的值.
(a+b)²=(a-b)²+4ab
=5²+4×3
=25+12
=37
3(a²+b²)=3[(a-b)²+2ab]
=3×(5²+2×3)
=3×(25+6)
=3×31
=93

(a+b)²
=a²+b²+2ab
=a²+b²-2ab+4ab
=(a-b)²+4ab
=25+12
=37
3(a²+b²)
=3(a²+b²+2ab-2ab)
=3[(a+b)²-2ab]
=3[37-6]
=3[31]
=93