Firstly, I'm not sure which section this goes in (so please don't infract me for it )
a) Differentiate from first principles
b) Find the gradient of the secant through the points. A(1,3) and B(3,11)
What is a secant?
c) Find the equation of the tangent to the curve at the point A
How would I go about doing this?
a) Assuming that you have evaluated and haven't simply used the rule, then you are correct.
b) A secant is a line that cuts through a curve in two or more points. So in other words, work out the equation of the line between and .
c) You know point lies on the tangent line. So you can substitute into . You can also evaluate , since the derivative tells you the gradient of the tangent line at any point (so evaluate it at ). Then you can solve for .