OCR MEI C2 2013 June — Question 1 5 marks

Exam BoardOCR MEI
ModuleC2 (Core Mathematics 2)
Year2013
SessionJune
Marks5
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicTangents, normals and gradients
TypeFind derivative of simple polynomial (integer powers)
DifficultyEasy -1.8 This is a straightforward differentiation exercise testing only the power rule on simple functions. Part (i) is direct application; part (ii) requires rewriting the root as a fractional power first. Both are routine recall with minimal steps, making this easier than average even for basic A-level questions.
Spec1.07i Differentiate x^n: for rational n and sums

Find \(\frac{dy}{dx}\) when
  1. \(y = 2x^{-5}\). [2]
  2. \(y = ^4\sqrt{x}\). [3]

Part (i)
AnswerMarks Guidance
\(-10x^{-6}\) iswB1 for \(-10\) or for \(x^{-6}\) ignore \(+c\) and \(y=\); if B0B0 then SC1 for \(-5x^2 \cdot x^{-1}\) or better soi
Part (ii)
AnswerMarks Guidance
\(y = x^{1/3}\) soi; \(kx^{n-1}\); \(\frac{1}{3}x^{-2/3}\) iswB1, M1, A1 condone \(y' = x^{1/3}\) if differentiation follows ft their fractional \(n\); ignore \(+c\) and \(y=\); allow 0.333 or better
### Part (i)
$-10x^{-6}$ isw | B1 | for $-10$ or for $x^{-6}$ ignore $+c$ and $y=$; if B0B0 then SC1 for $-5x^2 \cdot x^{-1}$ or better soi

### Part (ii)
$y = x^{1/3}$ soi; $kx^{n-1}$; $\frac{1}{3}x^{-2/3}$ isw | B1, M1, A1 | condone $y' = x^{1/3}$ if differentiation follows ft their fractional $n$; ignore $+c$ and $y=$; allow 0.333 or better
Find $\frac{dy}{dx}$ when
\begin{enumerate}[label=(\roman*)]
\item $y = 2x^{-5}$. [2]
\item $y = ^4\sqrt{x}$. [3]
\end{enumerate}

\hfill \mbox{\textit{OCR MEI C2 2013 Q1 [5]}}