已知a+b=-3,ab=1,求a²+b²的值.请详解,

已知a+b=-3,ab=1,求a²+b²的值.请详解,

a²+b²
=(a+b)²-2ab
把a+b=-3,ab=1代入上式,得
a²+b²
=(a+b)²-2ab
=(-3)²-2×1
=9-2
=7

123

a²+b²
=(a+b)²-2ab
=(-3)²-2*1
=7