4x^2+6x-10
=2(2x^2+3x+1)-12
=2×6-12
=0
(x+m)^2=x^2+nx+9
x^2+2m+m^2=x^2+nx+9
(2m-n)x+m^2-9=0
所以
2m-n=0且m^2-9=0
解得m=3,n=6或m=-3,n=-6