The point P P\,P lies on the curve with equation y=ln(13x)\displaystyle y = \ln(\frac{1}{3}x)y=ln(31x). The xxx-coordinate of P P\,P is 3. Find an equation of the normal to the curve at the point P P\,P in the form y=ax+by = ax + by=ax+b, where a a\,a and b b\,b are constants.
14 exam-style questions on Edexcel A Level Old Maths Differentiation. Each one has a worked solution and a mark scheme showing where the marks go.