f(x)=x2+6x+7 is a parabola. We convert this equation into vertex form to define the parabola.
f(x)=x2+6x+9-2=(x+3)2-2 has its vertex at (-3,-2). The vertex in this case is the minimum value of f(x), that is, when x=-3 and y=f(x)=-2. The axis of symmetry is x=-3. The y-intercept is y=f(x)=7. These parameters help to draw the parabola.