AQA FP1 2008 June — Question 4 9 marks

Exam BoardAQA
ModuleFP1 (Further Pure Mathematics 1)
Year2008
SessionJune
Marks9
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicGeneralised Binomial Theorem and Partial Fractions
TypePartial fractions then binomial expansion
DifficultyModerate -0.5 This is a straightforward data linearization problem requiring algebraic manipulation to show Y = aX + b, then plotting points and reading off gradient/intercept. The algebra is simple substitution, and the graphical work is routine. Below average difficulty for FP1 as it requires no advanced techniques, just careful arithmetic and basic linear regression concepts.
Spec1.06h Logarithmic graphs: reduce y=ax^n and y=kb^x to linear form2.02c Scatter diagrams and regression lines

4 [Figure 1 and Figure 2, printed on the insert, are provided for use in this question.]
The variables \(x\) and \(y\) are related by an equation of the form $$y = a x + \frac { b } { x + 2 }$$ where \(a\) and \(b\) are constants.
  1. The variables \(X\) and \(Y\) are defined by \(X = x ( x + 2 ) , Y = y ( x + 2 )\). Show that \(Y = a X + b\).
  2. The following approximate values of \(x\) and \(y\) have been found:
    \(x\)1234
    \(y\)0.401.432.403.35
    1. Complete the table in Figure 1, showing values of \(X\) and \(Y\).
    2. Draw on Figure 2 a linear graph relating \(X\) and \(Y\).
    3. Estimate the values of \(a\) and \(b\).

AnswerMarks Guidance
(a) Multiplication by \(x + 2\); \(Y = ax + b\) convincingly shownM1, A1 2 marks
(b)(i) \(X = 8, 15, 24\) in table; \(Y = 5.72, 12, 20.1\) in tableB1, B1 2 marks
(b)(ii) Four points plotted; Reasonable line drawnB1F, B1F 2 marks
(b)(iii) Method for gradient: \(a = \text{gradient} \approx 0.9\); \(b = Y\text{-intercept} \approx -1.5\)M1, A1, B1F 3 marks
Total: 9 marks
**(a)** Multiplication by $x + 2$; $Y = ax + b$ convincingly shown | M1, A1 | 2 marks | applied to all 3 terms; AG

**(b)(i)** $X = 8, 15, 24$ in table; $Y = 5.72, 12, 20.1$ in table | B1, B1 | 2 marks | Allow correct to 2SF

**(b)(ii)** Four points plotted; Reasonable line drawn | B1F, B1F | 2 marks | ft incorrect values in table; ft incorrect points

**(b)(iii)** Method for gradient: $a = \text{gradient} \approx 0.9$; $b = Y\text{-intercept} \approx -1.5$ | M1, A1, B1F | 3 marks | or algebraic method for $a$ or $b$; Allow from 0.88 to 0.93 incl; Allow from $-2$ to $-1$ inclusive; ft incorrect points/line; NMS B1 for $a$, B1 for $b$

**Total: 9 marks**
4 [Figure 1 and Figure 2, printed on the insert, are provided for use in this question.]\\
The variables $x$ and $y$ are related by an equation of the form

$$y = a x + \frac { b } { x + 2 }$$

where $a$ and $b$ are constants.
\begin{enumerate}[label=(\alph*)]
\item The variables $X$ and $Y$ are defined by $X = x ( x + 2 ) , Y = y ( x + 2 )$.

Show that $Y = a X + b$.
\item The following approximate values of $x$ and $y$ have been found:

\begin{center}
\begin{tabular}{ | c | c | c | c | c | }
\hline
$x$ & 1 & 2 & 3 & 4 \\
\hline
$y$ & 0.40 & 1.43 & 2.40 & 3.35 \\
\hline
\end{tabular}
\end{center}
\begin{enumerate}[label=(\roman*)]
\item Complete the table in Figure 1, showing values of $X$ and $Y$.
\item Draw on Figure 2 a linear graph relating $X$ and $Y$.
\item Estimate the values of $a$ and $b$.
\end{enumerate}\end{enumerate}

\hfill \mbox{\textit{AQA FP1 2008 Q4 [9]}}