The graph of y=x2+6x+9 is shown below. What is the solution set for x^2+6x+9=0?
{0,9}
{0,-3}
{-3,3}
{-3}

There is only one point in the solution set :

x = -3

Step-by-step explanation:

Notice that the function is a quadratic whose graph is represented by a parabola, When you are asked for the solution to the equation:

you are being asked about which values of the variable "x" render y = 0.

Notice as well, that the vertex of the parabola, is touching the x-axis. and recall that point on the x axis are those with y-value = 0.

Therefore, there is only one x-value for which this function will render zero. That value is x = -3.