Edexcel IALMathematicsGeneral Applications7 Marks
The curve C has equation y = (2x + 3)^3. (a) Find dy/dx. (b) Find the equation of the tangent to the curve C at the point where x = -1. Give your answer in the form y = mx + c.
- (a)Find dy/dx.[2]
- (b)Find the equation of the tangent to the curve C at the point where x = -1. Give your answer in the form y = mx + c.[5]
Mark scheme
Marking points from the official mark scheme. The mark or mark type is shown in brackets.
- M1 for attempting to use the chain rule: n(ax+b)^(n-1) * a (e.g., 3(2x+3)^2 * k).
- A1 for dy/dx = 6(2x + 3)^2.
- B1 for finding the y-coordinate of the point where x = -1: y = (2(-1) + 3)^3 = (1)^3 = 1.
- M1 for substituting x = -1 into dy/dx to find the gradient of the tangent.
- A1 for gradient m = 6(2(-1) + 3)^2 = 6(1)^2 = 6.
- M1 for using y - y1 = m(x - x1) with their found point and gradient.
- A1 for y = 6x + 7.
Write your answer and get it marked
On Oracle Prep you can write or photograph your own answer and have it marked by AI against this mark scheme, with feedback on what you missed.
Sign up free →