已知a+b=3,ab=-2,求a^2+b^2及(a-b)^2的值
问题描述:
已知a+b=3,ab=-2,求a^2+b^2及(a-b)^2的值
答
a²+b²
=(a+b)²-2ab
=3²-2×(-2)
=9+4
=13
(a-b)²
=(a+b)²-4ab
=3²-4×(-2)
=9+8
=17