This is homework, but the problem set is already due, but I don't understand how to get the answer to this problem and I'd really like to understand the thought process behind disseminating this problem.
On your own paper, sketch the graph of the parabola y = x^2 +8 . On the same graph, plot the point (0, −3) . Note that there are two tangent lines of y that pass through this point. (It may be useful to sketch them on your graph.) Specifically, the tangent line of the parabola y = x^2 +8 at the point (a, a^2+8) passes through the point (0, −3) where a>0. The other tangent line passing through this point goes through (−a, a^2+8) . Use this information to find the number a.