Resposta :
[tex] \sqrt{x^2+3} = x^2+1 \\
x^2+3=(x^2+1)^2 \\
x^2+3=x^4+2x^2+1 \\
x^4+2x^2-x^2+1-3=0 \\
x^4+x^2-2=0 \\
\boxed{y=x^2} \\
y^2+y-2=0 \\
\Delta=1^2-4.1.(-2)=1+8=9 \\
y_1=\frac{-1-3}{2}=-2 \\
\\
y_2=\frac{-1+3}{2}=1 \\
\\
x^2=1 \\
x_1=+1 \\
x_2=-1 \\
[/tex]