For a parabola equation of the form
[tex]g(x)=a\cdot(x-h)^2+k[/tex]The equation of the symmetry is
[tex]x=h[/tex]So, rewrite the given equation in the above form as follows:
[tex]\begin{gathered} g(x)=x^2+4x+3 \\ g(x)=x^2+2\cdot x\cdot2+2^2-2^2+3 \\ g(x)=(x+2)^2-4+3 \\ g(x)=(x+2)^2-1 \end{gathered}[/tex]Comparing g(x)=(x+2)^2-1 with g(x)=a(x-h)^2+k one can get, h=-2,k=-1.
So, the axis of symmetry is x=-2.
The correct option is B.
