Edexcel C3 — Question 3 10 marks

Exam BoardEdexcel
ModuleC3 (Core Mathematics 3)
Marks10
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicProduct & Quotient Rules
TypeFind derivative of product
DifficultyModerate -0.8 This is a straightforward multi-part differentiation question testing standard rules (chain rule for parts a and c, product rule for part b). Each part requires direct application of a single technique with minimal algebraic manipulation. This is easier than average as it's purely procedural with no problem-solving or insight required.
Spec1.07k Differentiate trig: sin(kx), cos(kx), tan(kx)1.07l Derivative of ln(x): and related functions1.07q Product and quotient rules: differentiation1.07r Chain rule: dy/dx = dy/du * du/dx and connected rates

3. Differentiate each of the following with respect to \(x\) and simplify your answers.
  1. \(\quad \ln ( \cos x )\)
  2. \(x ^ { 2 } \sin 3 x\)
  3. \(\frac { 6 } { \sqrt { 2 x - 7 } }\)

Part (a)
AnswerMarks
\(= \frac{-1}{\cos x} \times (-\sin x) = -\tan x\)M1 A2
Part (b)
AnswerMarks
\(= 2x \times \sin 3x + x^2 \times 3\cos 3x = 2x \sin 3x + 3x^2 \cos 3x\)M1 A2
Part (c)
AnswerMarks
\(= \frac{d}{dx}[6(2x-7)^{-\frac{1}{2}}]\)B1
\(= -3(2x-7)^{-\frac{3}{2}} \times 2 = -\frac{6}{(2x-7)^{\frac{3}{2}}}\)M1 A2
(10)
**Part (a)**
$= \frac{-1}{\cos x} \times (-\sin x) = -\tan x$ | M1 A2 |

**Part (b)**
$= 2x \times \sin 3x + x^2 \times 3\cos 3x = 2x \sin 3x + 3x^2 \cos 3x$ | M1 A2 |

**Part (c)**
$= \frac{d}{dx}[6(2x-7)^{-\frac{1}{2}}]$ | B1 |
$= -3(2x-7)^{-\frac{3}{2}} \times 2 = -\frac{6}{(2x-7)^{\frac{3}{2}}}$ | M1 A2 |
| (10) |

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3. Differentiate each of the following with respect to $x$ and simplify your answers.
\begin{enumerate}[label=(\alph*)]
\item $\quad \ln ( \cos x )$
\item $x ^ { 2 } \sin 3 x$
\item $\frac { 6 } { \sqrt { 2 x - 7 } }$
\end{enumerate}

\hfill \mbox{\textit{Edexcel C3  Q3 [10]}}