First, work out the slope of the secant line :

Which gives

Now that you know the slope of the secant line, you can derivate and find a derived point of which has the same slope as the secant line.

The derivate of is :

Now you want a slope of , right ? Therefore, you will want to solve the derivative like this :

Which gives :

Now solve this simple equation :

Factorize this (and by the way, on right-hand-side) :

Easy solve :

So, or

Now you know that the points that have x-coordinate and have a slope of on the first function. Substitute back into the first function to find their y-coordinate :

Let's conclude : when or , the tangent to this point of the function has a slope of , which is equal to the slope of the secant line .

So, the solutions are the points and .