已知(a^2)+(b^2)=50,(a+b)^2=8,求a-b的值
问题描述:
已知(a^2)+(b^2)=50,(a+b)^2=8,求a-b的值
答
(a+b)^2
=a²+b²+2ab
=50+2ab=8
得2ab=-42
a-b
=√(a-b)²
=√a²+b²-2ab
=√50+42
=2√23