已知a+b=7,ab=10,则a²+b²=______.
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![已知a+b=7,ab=10,则a²+b²=______.](/uploads/image/z/3835952-8-2.jpg?t=%E5%B7%B2%E7%9F%A5a%2Bb%3D7%2Cab%3D10%2C%E5%88%99a%26%23178%3B%2Bb%26%23178%3B%3D______.)
已知a+b=7,ab=10,则a²+b²=______.
已知a+b=7,ab=10,则a²+b²=______.
已知a+b=7,ab=10,则a²+b²=______.
a²+b²
=(a+b)²-2ab
=7²-2×10
=49-20
=29
a²+b²
=a²+b²+2ab-2ab
=(a+b)²-2ab
=49-20
=29
a²+b²=(a+b)²-2ab=49-20=29