(x-3)^2+5x^2=(2x+1)^2-x-1
x^2-6x+9+5x^2=4x^2+4x+1-x-1
6x^2-6x+9=4x^2+3x
6x^2-6x+9-4x^2-3x=0
2x^2-9x+9=0
a=2, b=-9, c=9
\Delta=b^2-4ac=81-4*2*9=81-72=9
\sqrt\Delta=3
x_1=\frac{-b-\sqrt\Delta}{2a}=\frac{9-3}{2*2}=\frac{6}{4}=\frac{3}{2}=1,5
x_2=\frac{-b+\sqrt\Delta}{2a}=\frac{9+3}{4}=\frac{12}{4}=3