| Exam Board | AQA |
|---|---|
| Module | AS Paper 1 (AS Paper 1) |
| Session | Specimen |
| Marks | 5 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Differentiation from First Principles |
| Type | Expand f(a+h) algebraically |
| Difficulty | Moderate -0.3 Part (a) is straightforward algebraic expansion and simplification. Part (b) is a standard first principles differentiation question at a specific point, requiring the limit definition but with routine algebraic manipulation. While it's a multi-step problem worth 5 marks total, both parts follow textbook procedures without requiring problem-solving insight, making it slightly easier than average for AS-level. |
| Spec | 1.07a Derivative as gradient: of tangent to curve1.07g Differentiation from first principles: for small positive integer powers of x |
| Answer | Marks |
|---|---|
| 9(a) | Substitutes 3 + h to obtain a |
| Answer | Marks | Guidance |
|---|---|---|
| for f(3 + h) | AO1.1a | M1 |
| Answer | Marks | Guidance |
|---|---|---|
| correctly in given format | AO1.1b | A1 |
| (b) | Identifies and uses |
| Answer | Marks | Guidance |
|---|---|---|
| unsimplified expression. | AO1.1a | M1 |
| Answer | Marks | Guidance |
|---|---|---|
| simplification | AO1.1b | A1 |
| Answer | Marks | Guidance |
|---|---|---|
| has been awarded | AO2.2a | R1 |
| Total | 5 | |
| Q | Marking Instructions | AO |
Question 9:
--- 9(a) ---
9(a) | Substitutes 3 + h to obtain a
correct unsimplified expression
for f(3 + h) | AO1.1a | M1 | (3h)2 4(3h)2
or
=96hh2124h2
=h22h1
Expresses simplified answer
correctly in given format | AO1.1b | A1
(b) | Identifies and uses
f(xh)f(x)
to obtain an
h
expression for the gradient of
chord
Mark can be awarded for
unsimplified expression. | AO1.1a | M1 | f(3h)f(3)
Gradient of chord =
h
h2 2h11
h
h2
As h0, h22
Gradient of tangent = 2
Obtains a correct and full
simplification | AO1.1b | A1
Deduces that, as h approaches
f(3h)f(3)
0 the limit of
h
is 2
(Must not simply say h = 0 but
accept words rather than limit
notation)
FT ‘their’ gradient provided M1
has been awarded | AO2.2a | R1
Total | 5
Q | Marking Instructions | AO | Marks | Typical Solution
\begin{enumerate}[label=(\alph*)]
\item Given that $f(x) = x^2 - 4x + 2$, find $f(3 + h)$
Express your answer in the form $h^2 + bh + c$, where $b$ and $c \in \mathbb{Z}$.
[2 marks]
\item The curve with equation $y = x^2 - 4x + 2$ passes through the point $P(3, -1)$ and the point $Q$ where $x = 3 + h$.
Using differentiation from first principles, find the gradient of the tangent to the curve at the point $P$.
[3 marks]
\end{enumerate}
\hfill \mbox{\textit{AQA AS Paper 1 Q9 [5]}}