AQA FP1 2006 June — Question 8 10 marks

Exam BoardAQA
ModuleFP1 (Further Pure Mathematics 1)
Year2006
SessionJune
Marks10
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicNewton-Raphson method
TypeIntersection of curves via iteration
DifficultyStandard +0.3 This is a multi-part question covering standard A-level techniques: binomial expansion of f(1+h), derivative from first principles, setting up an equation from curve intersection, one iteration of Newton-Raphson with given formula and starting value, and a routine improper integral. Each part is straightforward recall/application with no novel insight required, making it slightly easier than average.
Spec1.07g Differentiation from first principles: for small positive integer powers of x1.09d Newton-Raphson method4.08c Improper integrals: infinite limits or discontinuous integrands

8
  1. The function f is defined for all real values of \(x\) by $$\mathrm { f } ( x ) = x ^ { 3 } + x ^ { 2 } - 1$$
    1. Express \(\mathrm { f } ( 1 + h ) - \mathrm { f } ( 1 )\) in the form $$p h + q h ^ { 2 } + r h ^ { 3 }$$ where \(p , q\) and \(r\) are integers.
    2. Use your answer to part (a)(i) to find the value of \(f ^ { \prime } ( 1 )\).
  2. The diagram shows the graphs of $$y = \frac { 1 } { x ^ { 2 } } \quad \text { and } \quad y = x + 1 \quad \text { for } \quad x > 0$$
    \includegraphics[max width=\textwidth, alt={}]{e44987a7-2cdf-442a-aecb-abd3e889ecd4-5_643_791_1160_596}
    The graphs intersect at the point \(P\).
    1. Show that the \(x\)-coordinate of \(P\) satisfies the equation \(\mathrm { f } ( x ) = 0\), where f is the function defined in part (a).
    2. Taking \(x _ { 1 } = 1\) as a first approximation to the root of the equation \(\mathrm { f } ( x ) = 0\), use the Newton-Raphson method to find a second approximation \(x _ { 2 }\) to the root.
      (3 marks)
  3. The region enclosed by the curve \(y = \frac { 1 } { x ^ { 2 } }\), the line \(x = 1\) and the \(x\)-axis is shaded on the diagram. By evaluating an improper integral, find the area of this region.
    (3 marks)

Question 8:
Part (a)(i)
AnswerMarks Guidance
WorkingMarks Guidance
\((1+h)^3 = 1 + 3h + 3h^2 + h^3\)B1
\(f(1+h) = 1 + 5h + 4h^2 + h^3\)M1A1\(\checkmark\) PI; ft wrong coefficients
\(f(1+h) - f(1) = 5h + 4h^2 + h^3\)A1\(\checkmark\) (4) ft numerical errors
Part (a)(ii)
AnswerMarks Guidance
WorkingMarks Guidance
Dividing by \(h\)M1
\(f'(1) = 5\)A1\(\checkmark\) (2) ft numerical errors
Part (b)(i)
AnswerMarks Guidance
WorkingMarks Guidance
\(x^2(x+1) = 1\), hence resultB1 (1) Convincingly shown AG
Part (b)(ii)
AnswerMarks Guidance
WorkingMarks Guidance
\(x_2 = 1 - \frac{1}{5} = \frac{4}{5}\)M1A1\(\checkmark\), A1\(\checkmark\) (3) ft c's value of \(f'(1)\)
Part (c)
AnswerMarks Guidance
WorkingMarks Guidance
Area \(= \int_1^{\infty} x^{-2}\, dx\)M1
\(= \left[-x^{-1}\right]_1^{\infty}\)M1 Ignore limits here
\(= 0 - -1 = 1\)A1 (3)
## Question 8:

### Part (a)(i)
| Working | Marks | Guidance |
|---------|-------|----------|
| $(1+h)^3 = 1 + 3h + 3h^2 + h^3$ | B1 | |
| $f(1+h) = 1 + 5h + 4h^2 + h^3$ | M1A1$\checkmark$ | PI; ft wrong coefficients |
| $f(1+h) - f(1) = 5h + 4h^2 + h^3$ | A1$\checkmark$ (4) | ft numerical errors |

### Part (a)(ii)
| Working | Marks | Guidance |
|---------|-------|----------|
| Dividing by $h$ | M1 | |
| $f'(1) = 5$ | A1$\checkmark$ (2) | ft numerical errors |

### Part (b)(i)
| Working | Marks | Guidance |
|---------|-------|----------|
| $x^2(x+1) = 1$, hence result | B1 (1) | Convincingly shown AG |

### Part (b)(ii)
| Working | Marks | Guidance |
|---------|-------|----------|
| $x_2 = 1 - \frac{1}{5} = \frac{4}{5}$ | M1A1$\checkmark$, A1$\checkmark$ (3) | ft c's value of $f'(1)$ |

### Part (c)
| Working | Marks | Guidance |
|---------|-------|----------|
| Area $= \int_1^{\infty} x^{-2}\, dx$ | M1 | |
| $= \left[-x^{-1}\right]_1^{\infty}$ | M1 | Ignore limits here |
| $= 0 - -1 = 1$ | A1 (3) | |

---
8
\begin{enumerate}[label=(\alph*)]
\item The function f is defined for all real values of $x$ by

$$\mathrm { f } ( x ) = x ^ { 3 } + x ^ { 2 } - 1$$
\begin{enumerate}[label=(\roman*)]
\item Express $\mathrm { f } ( 1 + h ) - \mathrm { f } ( 1 )$ in the form

$$p h + q h ^ { 2 } + r h ^ { 3 }$$

where $p , q$ and $r$ are integers.
\item Use your answer to part (a)(i) to find the value of $f ^ { \prime } ( 1 )$.
\end{enumerate}\item The diagram shows the graphs of

$$y = \frac { 1 } { x ^ { 2 } } \quad \text { and } \quad y = x + 1 \quad \text { for } \quad x > 0$$

\begin{center}
\includegraphics[max width=\textwidth, alt={}]{e44987a7-2cdf-442a-aecb-abd3e889ecd4-5_643_791_1160_596}
\end{center}

The graphs intersect at the point $P$.
\begin{enumerate}[label=(\roman*)]
\item Show that the $x$-coordinate of $P$ satisfies the equation $\mathrm { f } ( x ) = 0$, where f is the function defined in part (a).
\item Taking $x _ { 1 } = 1$ as a first approximation to the root of the equation $\mathrm { f } ( x ) = 0$, use the Newton-Raphson method to find a second approximation $x _ { 2 }$ to the root.\\
(3 marks)
\end{enumerate}\item The region enclosed by the curve $y = \frac { 1 } { x ^ { 2 } }$, the line $x = 1$ and the $x$-axis is shaded on the diagram. By evaluating an improper integral, find the area of this region.\\
(3 marks)
\end{enumerate}

\hfill \mbox{\textit{AQA FP1 2006 Q8 [10]}}