x1,x2是方程的根,由韦达定理得x1+x2=3
x1代入方程,得x1²-3x1+1=0
x1²=3x1-1
4x1²+12x2+11
=4(3x1-1)+12x2+11
=12x1+12x2-4+11
=12(x1+x2)+7
=12×3+7
=43