You might find some of the ideas in Slippery slopes helpful when thinking about this problem.
Here are the graphs of \(y=\dfrac{1}{x}\) and \(y=\dfrac{1}{x+1}\) with tangents drawn at points A and B.
What happens when you move the point A? (Be careful when the \(x\)-coordinate of A gets close to \(-1\).)
How could you work out the gradient of \(y=\dfrac{1}{x+1}\) at the point \((2,\tfrac{1}{3})\)?
How can you differentiate \(\dfrac{1}{x+1}\)?
How could you adapt these approaches to work out the derivative of \(\dfrac{1}{2x+1}\)?
Can you suggest other examples where you could use a similar approach to find derivatives?
In this problem we have only composed the function \(\dfrac{1}{x}\) with functions of the form \(ax+b\). Could you apply any of these ideas to polynomial, rational or trigonometric functions?
