CAIE P2 2017 June — Question 4 5 marks

Exam BoardCAIE
ModuleP2 (Pure Mathematics 2)
Year2017
SessionJune
Marks5
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicProduct & Quotient Rules
TypeFind equation of tangent
DifficultyModerate -0.8 This is a straightforward application of the quotient rule to find dy/dx, followed by routine evaluation at x=0 to find the gradient and y-coordinate, then forming the tangent equation. All steps are standard with no problem-solving required, making it easier than average but not trivial due to the exponential function and algebraic manipulation needed.
Spec1.07j Differentiate exponentials: e^(kx) and a^(kx)1.07m Tangents and normals: gradient and equations1.07q Product and quotient rules: differentiation

4 Find the equation of the tangent to the curve \(y = \frac { \mathrm { e } ^ { 4 x } } { 2 x + 3 }\) at the point on the curve for which \(x = 0\). Give your answer in the form \(a x + b y + c = 0\) where \(a , b\) and \(c\) are integers.

Question 4:
AnswerMarks Guidance
AnswerMark Guidance
Use quotient rule (or product rule) to find first derivativeM1
Obtain \(\dfrac{8xe^{4x}+10e^{4x}}{(2x+3)^2}\) or equivalentA1
Substitute \(x=0\) to obtain gradient \(\frac{10}{9}\)A1
Form equation of tangent through \(\left(0, \frac{1}{3}\right)\) with numerical gradientM1
Obtain \(10x - 9y + 3 = 0\)A1
Total:5
## Question 4:

| Answer | Mark | Guidance |
|--------|------|----------|
| Use quotient rule (or product rule) to find first derivative | M1 | |
| Obtain $\dfrac{8xe^{4x}+10e^{4x}}{(2x+3)^2}$ or equivalent | A1 | |
| Substitute $x=0$ to obtain gradient $\frac{10}{9}$ | A1 | |
| Form equation of tangent through $\left(0, \frac{1}{3}\right)$ with numerical gradient | M1 | |
| Obtain $10x - 9y + 3 = 0$ | A1 | |
| **Total:** | **5** | |

---
4 Find the equation of the tangent to the curve $y = \frac { \mathrm { e } ^ { 4 x } } { 2 x + 3 }$ at the point on the curve for which $x = 0$. Give your answer in the form $a x + b y + c = 0$ where $a , b$ and $c$ are integers.\\

\hfill \mbox{\textit{CAIE P2 2017 Q4 [5]}}