sagnol
幼苗
共回答了18个问题采纳率：94.4% 举报
m,n是一元二次方程x2-2x-5=0的两个实数根
所以m+n=2,mn=-5
所以(m+n)^2=m^2+n^2+2mn=4
m^2+n^2=4-2mn=14
2m^2+3n^2+2m
=2m^2+2n^2+n^2+2m
=2(m^2+n^2)+n^2+2m
=28+n^2+2m
因为n是一元二次方程x2-2x-5=0的根
所以n^2-2n-5=0
n^2=2n+5
所以2m^2+3n^2+2m
=28+n^2+2m
=28+2n++5+2m
=33+2(m+n)
=37
1年前
10
