f(x)=x^2-2x+4x=1+ 2sqrt(3)f(1+ 2sqrt(3))=(1+ 2sqrt(3))^2-2(1+ 2sqrt(3))+4 = (1+4sqrt(3)+4*3)-2 - 4sqrt(3)+4 = 15
f(x)=x^2-2x+4x=1+ 2sqrt(3)f(1+ 2sqrt(3))=(1+ 2sqrt(3))^2-2(1+ 2sqrt(3))+4 = (1+4sqrt(3)+4*3)-2 - 4sqrt(3)+4 = 15