x^4+4x^3+3x^2+8x-4
=(x^4+4x^3+4x^2)-(x^2+8x+16)+12
=x^2(x+2)^2-(x+4)^2+12
=(根号3-2)^2*(根号3)^2-(根号3+2)^2+12
=3(3-4根号3+4)-(3+4根号3+4)+12
=26-16根号3