Introduction to the investigation

This is how you might start your investigation...

I looked at the graph y = x2.

x = 3, f'(x) = 6
x = 5, f'(x) = 10

I noticed that f(x) is always 2 multiplied by x. So, f(x) = x2, f'(x) = 2x.

Next I will try x2 + 1.