设实数m,n满足19m^2+20m+1=0,n^2+20n+19=0且mn不等于0,求2mn+3m+2/n的值
问题描述：
设实数m,n满足19m^2+20m+1=0,n^2+20n+19=0且mn不等于0,求2mn+3m+2/n的值
答
m=(-20± √20^2-4*19*1)/2*19 =(-20±18)/38 =-1/19 或-1
n=(-20± √20^2-4*19*1)/2*1 =(-20±18)/2 =-1 或-19
2mn+3m+2/n =2/19-3/19-2 =-39/19 m=-1/19 ,n=-1
2mn+3m+2/n =2-3-2 =-3 m=-1 ,n=-1
2mn+3m+2/n =2-20/19-2/19 =16/19 m=-1/19 ,n=-19
2mn+3m+2/n =38-3-2/19 =663/19 m=-1 ,n=-19