OCR PURE — Question 1 8 marks

Exam BoardOCR
ModulePURE
Marks8
PaperDownload PDF ↗
TopicDifferentiating Transcendental Functions
TypeDifferentiate exponential functions
DifficultyEasy -1.2 This is a straightforward differentiation and integration question using basic power rule only. Despite the title mentioning transcendental functions, the actual question involves only polynomial terms (x and x^{-3}), requiring simple application of standard rules with no problem-solving or conceptual challenge. Easier than average A-level content.
Spec1.07e Second derivative: as rate of change of gradient1.07i Differentiate x^n: for rational n and sums1.08b Integrate x^n: where n != -1 and sums

1 It is given that \(\mathrm { f } ( x ) = 3 x - \frac { 5 } { x ^ { 3 } }\).
Find
  1. \(\mathrm { f } ^ { \prime } ( x )\),
  2. \(\mathrm { f } ^ { \prime \prime } ( x )\),
  3. \(\int \mathrm { f } ( x ) \mathrm { d } x\).

Question 1:
*Note: In all three parts: Allow unsimplified answers. ISW for incorrect simplification. Ignore incorrect dx and/or ∫*
Part (a)
\(3 + 15x^{-4}\) or \(3 + \frac{15}{x^4}\) oe
AnswerMarks Guidance
AnswerMark Guidance
\(3x\) correctly differentiated to \(3\)B1 (1.1)
\(kx^{-4}\) oeM1 (1.1a)
\(15x^{-4}\) or \(\frac{15}{x^4}\) oeA1 (1.1) ISW e.g. \(5 \times 3x^{-4} = \frac{5}{3x^4}\) M1A1
[3]
Part (b)
\(-60x^{-5}\) or \(-\frac{60}{x^5}\) oe
AnswerMarks Guidance
AnswerMark Guidance
Zero term stated or implied by absenceB1f (1.1a) Or ft their 1st term in (a)
Other term, ft their 2nd term in (a) if includes negative indexB1f (1.1) ISW
[2]
Part (c)
\(\frac{3x^2}{2} + \frac{5}{2}x^{-2} + c\) or \(\frac{3x^2}{2} + \frac{5}{2x^2} + c\) oe
AnswerMarks Guidance
AnswerMark Guidance
\(\frac{3x^2}{2}\)B1 (1.1)
\(kx^{-2}\) oeM1 (1.1a)
All correct and \(+ c\)A1 (1.1) ISW
[3]
## Question 1:

*Note: In all three parts: Allow unsimplified answers. ISW for incorrect simplification. Ignore incorrect dx and/or ∫*

### Part (a)
$3 + 15x^{-4}$ or $3 + \frac{15}{x^4}$ oe

| Answer | Mark | Guidance |
|--------|------|----------|
| $3x$ correctly differentiated to $3$ | B1 (1.1) | |
| $kx^{-4}$ oe | M1 (1.1a) | |
| $15x^{-4}$ or $\frac{15}{x^4}$ oe | A1 (1.1) | ISW e.g. $5 \times 3x^{-4} = \frac{5}{3x^4}$ M1A1 |
| **[3]** | | |

### Part (b)
$-60x^{-5}$ or $-\frac{60}{x^5}$ oe

| Answer | Mark | Guidance |
|--------|------|----------|
| Zero term stated or implied by absence | B1f (1.1a) | Or ft their 1st term in (a) |
| Other term, ft their 2nd term in (a) if includes negative index | B1f (1.1) | ISW |
| **[2]** | | |

### Part (c)
$\frac{3x^2}{2} + \frac{5}{2}x^{-2} + c$ or $\frac{3x^2}{2} + \frac{5}{2x^2} + c$ oe

| Answer | Mark | Guidance |
|--------|------|----------|
| $\frac{3x^2}{2}$ | B1 (1.1) | |
| $kx^{-2}$ oe | M1 (1.1a) | |
| All correct and $+ c$ | A1 (1.1) | ISW |
| **[3]** | | |

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1 It is given that $\mathrm { f } ( x ) = 3 x - \frac { 5 } { x ^ { 3 } }$.\\
Find
\begin{enumerate}[label=(\alph*)]
\item $\mathrm { f } ^ { \prime } ( x )$,
\item $\mathrm { f } ^ { \prime \prime } ( x )$,
\item $\int \mathrm { f } ( x ) \mathrm { d } x$.
\end{enumerate}

\hfill \mbox{\textit{OCR PURE  Q1 [8]}}