CAIE P2 2019 March — Question 3 5 marks

Exam BoardCAIE
ModuleP2 (Pure Mathematics 2)
Year2019
SessionMarch
Marks5
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicExponential Functions
TypeLinear transformation to find constants
DifficultyModerate -0.5 This is a standard linear transformation question requiring students to take logarithms of an exponential equation to obtain a straight line, then use two given points to find the gradient and intercept. The algebraic manipulation is straightforward with clear steps: ln y = ln A + px + p gives a linear form, find p from gradient, then find A from the y-intercept. Slightly easier than average as it's a well-practiced technique with no conceptual surprises.
Spec1.06h Logarithmic graphs: reduce y=ax^n and y=kb^x to linear form

3 \includegraphics[max width=\textwidth, alt={}, center]{772c14a1-f79a-4147-a293-0ff34f930e20-04_577_569_260_788} The variables \(x\) and \(y\) satisfy the equation \(y = A \mathrm { e } ^ { p x + p }\), where \(A\) and \(p\) are constants. The graph of \(\ln y\) against \(x\) is a straight line passing through the points \(( 1,2.835 )\) and \(( 6,6.585 )\), as shown in the diagram. Find the values of \(A\) and \(p\).

Question 3:
AnswerMarks Guidance
AnswerMark Guidance
State or imply equation is \(\ln y = \ln A + px + p\)B1
Equate gradient of line to \(p\)M1
Obtain \(p = 0.75\)A1
Substitute appropriate values to find \(\ln A\)M1
Obtain \(\ln A = 1.335...\) and hence \(A = 3.8\)A1
## Question 3:

| Answer | Mark | Guidance |
|--------|------|----------|
| State or imply equation is $\ln y = \ln A + px + p$ | B1 | |
| Equate gradient of line to $p$ | M1 | |
| Obtain $p = 0.75$ | A1 | |
| Substitute appropriate values to find $\ln A$ | M1 | |
| Obtain $\ln A = 1.335...$ and hence $A = 3.8$ | A1 | |

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3\\
\includegraphics[max width=\textwidth, alt={}, center]{772c14a1-f79a-4147-a293-0ff34f930e20-04_577_569_260_788}

The variables $x$ and $y$ satisfy the equation $y = A \mathrm { e } ^ { p x + p }$, where $A$ and $p$ are constants. The graph of $\ln y$ against $x$ is a straight line passing through the points $( 1,2.835 )$ and $( 6,6.585 )$, as shown in the diagram. Find the values of $A$ and $p$.\\

\hfill \mbox{\textit{CAIE P2 2019 Q3 [5]}}