AQA FP1 2007 June — Question 9 15 marks

Exam BoardAQA
ModuleFP1 (Further Pure Mathematics 1)
Year2007
SessionJune
Marks15
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicStraight Lines & Coordinate Geometry
TypeLine and curve intersection
DifficultyStandard +0.3 This is a structured multi-part question on ellipse translation and tangency conditions. Parts (a)-(c) involve routine coordinate geometry (finding intercepts, applying translations, substituting to form a quadratic). Part (d) uses the discriminant condition for tangency (b²-4ac=0), which is standard FP1 material. The algebraic manipulation is straightforward, and the question guides students through each step methodically. Slightly easier than average due to its scaffolded nature.
Spec1.02c Simultaneous equations: two variables by elimination and substitution1.02d Quadratic functions: graphs and discriminant conditions1.02f Solve quadratic equations: including in a function of unknown1.02w Graph transformations: simple transformations of f(x)1.03d Circles: equation (x-a)^2+(y-b)^2=r^2

9 [Figure 3, printed on the insert, is provided for use in this question.]
The diagram shows the curve with equation $$\frac { x ^ { 2 } } { 2 } + y ^ { 2 } = 1$$ and the straight line with equation $$x + y = 2$$ \includegraphics[max width=\textwidth, alt={}, center]{354cbeda-d84e-433a-8834-a6f20e7e9513-05_805_1499_863_267}
  1. Write down the exact coordinates of the points where the curve with equation \(\frac { x ^ { 2 } } { 2 } + y ^ { 2 } = 1\) intersects the coordinate axes.
  2. The curve is translated \(k\) units in the positive \(x\) direction, where \(k\) is a constant. Write down, in terms of \(k\), the equation of the curve after this translation.
  3. Show that, if the line \(x + y = 2\) intersects the translated curve, the \(x\)-coordinates of the points of intersection must satisfy the equation $$3 x ^ { 2 } - 2 ( k + 4 ) x + \left( k ^ { 2 } + 6 \right) = 0$$
  4. Hence find the two values of \(k\) for which the line \(x + y = 2\) is a tangent to the translated curve. Give your answer in the form \(p \pm \sqrt { q }\), where \(p\) and \(q\) are integers.
  5. On Figure 3, show the translated curves corresponding to these two values of \(k\). \end{table} \begin{figure}[h]
    \captionsetup{labelformat=empty} \caption{Figure 2 (for use in Question 5)} \includegraphics[alt={},max width=\textwidth]{354cbeda-d84e-433a-8834-a6f20e7e9513-10_677_1056_886_466}
    \end{figure} \begin{figure}[h]
    \captionsetup{labelformat=empty} \caption{Figure 3 (for use in Question 9)} \includegraphics[alt={},max width=\textwidth]{354cbeda-d84e-433a-8834-a6f20e7e9513-10_798_1488_1891_274}
    \end{figure}

AnswerMarks Guidance
(a) Intersections \(\left(\pm\sqrt{2}, 0\right)\), \((0, \pm 1)\)B1B1 Allow B1 for \(\left(\sqrt{2}, 0\right)\), \((0, 1)\)
Total: 2 marks
AnswerMarks Guidance
(b) Equation is \(\frac{(x-k)^2}{2} + y^2 = 1\)M1A1 M1 if only one small error, eg \(x + k\) for \(x - k\)
Total: 2 marks
AnswerMarks Guidance
(c) Correct elimination of \(y\)M1
Correct expansion of squaresM1
Correct removal of denominatorM1
Answer convincingly establishedA1 AG
Total: 4 marks
AnswerMarks Guidance
(d) Tgt \(\Rightarrow 4(k+4)^2 - 12(k^2 + 6) = 0\)M1
\(\ldots \Rightarrow k^2 - 4k + 1 = 0\)m1A1 OE
\(\ldots \Rightarrow k = 2\pm\sqrt{3}\)A1
Total: 4 marks
AnswerMarks Guidance
(e) Curve to left of lineB1
Curve to right of lineB2 Curves must touch the line in approx correct positions
SC 1/3 if both curves are incomplete but touch the line correctly
Total: 3 marks
TOTAL: 75 marks
**(a)** Intersections $\left(\pm\sqrt{2}, 0\right)$, $(0, \pm 1)$ | B1B1 | Allow B1 for $\left(\sqrt{2}, 0\right)$, $(0, 1)$

**Total: 2 marks**

**(b)** Equation is $\frac{(x-k)^2}{2} + y^2 = 1$ | M1A1 | M1 if only one small error, eg $x + k$ for $x - k$

**Total: 2 marks**

**(c)** Correct elimination of $y$ | M1 |
Correct expansion of squares | M1 |
Correct removal of denominator | M1 |
Answer convincingly established | A1 | AG

**Total: 4 marks**

**(d)** Tgt $\Rightarrow 4(k+4)^2 - 12(k^2 + 6) = 0$ | M1 |
$\ldots \Rightarrow k^2 - 4k + 1 = 0$ | m1A1 | OE
$\ldots \Rightarrow k = 2\pm\sqrt{3}$ | A1 |

**Total: 4 marks**

**(e)** Curve to left of line | B1 |
Curve to right of line | B2 | Curves must touch the line in approx correct positions
| | | SC 1/3 if both curves are incomplete but touch the line correctly

**Total: 3 marks**

---

**TOTAL: 75 marks**
9 [Figure 3, printed on the insert, is provided for use in this question.]\\
The diagram shows the curve with equation

$$\frac { x ^ { 2 } } { 2 } + y ^ { 2 } = 1$$

and the straight line with equation

$$x + y = 2$$

\includegraphics[max width=\textwidth, alt={}, center]{354cbeda-d84e-433a-8834-a6f20e7e9513-05_805_1499_863_267}
\begin{enumerate}[label=(\alph*)]
\item Write down the exact coordinates of the points where the curve with equation $\frac { x ^ { 2 } } { 2 } + y ^ { 2 } = 1$ intersects the coordinate axes.
\item The curve is translated $k$ units in the positive $x$ direction, where $k$ is a constant. Write down, in terms of $k$, the equation of the curve after this translation.
\item Show that, if the line $x + y = 2$ intersects the translated curve, the $x$-coordinates of the points of intersection must satisfy the equation

$$3 x ^ { 2 } - 2 ( k + 4 ) x + \left( k ^ { 2 } + 6 \right) = 0$$
\item Hence find the two values of $k$ for which the line $x + y = 2$ is a tangent to the translated curve. Give your answer in the form $p \pm \sqrt { q }$, where $p$ and $q$ are integers.
\item On Figure 3, show the translated curves corresponding to these two values of $k$.

\end{table}

\begin{figure}[h]
\begin{center}
\captionsetup{labelformat=empty}
\caption{Figure 2 (for use in Question 5)}
  \includegraphics[alt={},max width=\textwidth]{354cbeda-d84e-433a-8834-a6f20e7e9513-10_677_1056_886_466}
\end{center}
\end{figure}

\begin{figure}[h]
\begin{center}
\captionsetup{labelformat=empty}
\caption{Figure 3 (for use in Question 9)}
  \includegraphics[alt={},max width=\textwidth]{354cbeda-d84e-433a-8834-a6f20e7e9513-10_798_1488_1891_274}
\end{center}
\end{figure}
\end{enumerate}

\hfill \mbox{\textit{AQA FP1 2007 Q9 [15]}}