两不等的实数m,n满足2m^2+m-4=0,2n^2+n-4=0.求m^2+n^2的值
问题描述：
两不等的实数m,n满足2m^2+m-4=0,2n^2+n-4=0.求m^2+n^2的值
答
两实数是方程2x^2+x-4=0的两根.
m+n=-1/2
mn=-2
m^2+n^2
=(m+n)^2-2mn
=1/4+4
=17/4