CAIE P2 2017 November — Question 6 9 marks

Exam BoardCAIE
ModuleP2 (Pure Mathematics 2)
Year2017
SessionNovember
Marks9
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicParametric differentiation
TypeFind stationary points of parametric curve
DifficultyStandard +0.3 This is a standard parametric differentiation question requiring dy/dx = (dy/dt)/(dx/dt), solving dy/dx = 0 for stationary points, and finding a normal gradient. The exponential functions add mild algebraic complexity, but the techniques are routine A-level procedures with no novel problem-solving required.
Spec1.03g Parametric equations: of curves and conversion to cartesian1.07s Parametric and implicit differentiation

6 The parametric equations of a curve are $$x = 2 \mathrm { e } ^ { 2 t } + 4 \mathrm { e } ^ { t } , \quad y = 5 t \mathrm { e } ^ { 2 t }$$
  1. Find \(\frac { \mathrm { d } y } { \mathrm {~d} x }\) in terms of \(t\) and hence find the coordinates of the stationary point, giving each coordinate correct to 2 decimal places.
  2. Find the gradient of the normal to the curve at the point where the curve crosses the \(x\)-axis.

Question 6(ii):
AnswerMarks Guidance
AnswerMark Guidance
Identify \(t = 0\)B1
Substitute \(t = 0\) in expression for first derivative and find negative reciprocalM1
Obtain \(-\frac{8}{3}\) or equivalentA1
Total: 3
## Question 6(ii):

| Answer | Mark | Guidance |
|--------|------|----------|
| Identify $t = 0$ | **B1** | |
| Substitute $t = 0$ in expression for first derivative and find negative reciprocal | **M1** | |
| Obtain $-\frac{8}{3}$ or equivalent | **A1** | |
| **Total: 3** | | |

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6 The parametric equations of a curve are

$$x = 2 \mathrm { e } ^ { 2 t } + 4 \mathrm { e } ^ { t } , \quad y = 5 t \mathrm { e } ^ { 2 t }$$

(i) Find $\frac { \mathrm { d } y } { \mathrm {~d} x }$ in terms of $t$ and hence find the coordinates of the stationary point, giving each coordinate correct to 2 decimal places.\\

(ii) Find the gradient of the normal to the curve at the point where the curve crosses the $x$-axis.\\

\hfill \mbox{\textit{CAIE P2 2017 Q6 [9]}}