Edexcel FP2 2010 June — Question 6 10 marks

Exam BoardEdexcel
ModuleFP2 (Further Pure Mathematics 2)
Year2010
SessionJune
Marks10
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicComplex Numbers Argand & Loci
TypeComplex transformations and mappings
DifficultyChallenging +1.2 This is a multi-part Further Maths question involving standard loci (perpendicular bisector and circle intersection) and a transformation. Part (a) is routine, part (b) requires solving simultaneous equations but is mechanical, and part (c) involves algebraic manipulation to show the image is a circle. While it requires multiple techniques, each step follows standard FP2 procedures without requiring novel insight or particularly challenging problem-solving.
Spec4.02a Complex numbers: real/imaginary parts, modulus, argument4.02k Argand diagrams: geometric interpretation4.02l Geometrical effects: conjugate, addition, subtraction

6. A complex number \(z\) is represented by the point \(P\) in the Argand diagram.
  1. Given that \(| z - 6 | = | z |\), sketch the locus of \(P\).
  2. Find the complex numbers \(z\) which satisfy both \(| z - 6 | = | z |\) and \(| z - 3 - 4 \mathrm { i } | = 5\). The transformation \(T\) from the \(z\)-plane to the \(w\)-plane is given by \(w = \frac { 30 } { z }\).
  3. Show that \(T\) maps \(| z - 6 | = | z |\) onto a circle in the \(w\)-plane and give the cartesian equation of this circle.

Question 6:
Part (a):
AnswerMarks Guidance
Answer/WorkingMarks Guidance
Vertical straight line drawnB1
Line passes through \(\text{Re}(z) = 3\) on real axisB1 (2 marks total)
Part (b):
AnswerMarks Guidance
Answer/WorkingMarks Guidance
Points where line \(x=3\) meets circle centre \((3,4)\) with radius \(5\)M1
Complex numbers are \(3 + 9i\) and \(3 - i\)A1 A1 (3 marks total)
Part (c):
AnswerMarks Guidance
Answer/WorkingMarks Guidance
\(\z-6\ = \
\(\therefore \30 - 6w\ = \
Circle with Cartesian equation \((u-5)^2 + v^2 = 25\)M1 A1 (5 marks total)
## Question 6:

### Part (a):

| Answer/Working | Marks | Guidance |
|---|---|---|
| Vertical straight line drawn | B1 | |
| Line passes through $\text{Re}(z) = 3$ on real axis | B1 | (2 marks total) |

### Part (b):

| Answer/Working | Marks | Guidance |
|---|---|---|
| Points where line $x=3$ meets circle centre $(3,4)$ with radius $5$ | M1 | |
| Complex numbers are $3 + 9i$ and $3 - i$ | A1 A1 | (3 marks total) |

### Part (c):

| Answer/Working | Marks | Guidance |
|---|---|---|
| $\|z-6\| = \|z\| \Rightarrow \left\|\frac{30}{w} - 6\right\| = \left\|\frac{30}{w}\right\|$ | M1 | |
| $\therefore \|30 - 6w\| = \|30\| \Rightarrow \therefore \|5 - w\| = \|5\|$ | M1 A1 | |
| Circle with Cartesian equation $(u-5)^2 + v^2 = 25$ | M1 A1 | (5 marks total) |

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6. A complex number $z$ is represented by the point $P$ in the Argand diagram.
\begin{enumerate}[label=(\alph*)]
\item Given that $| z - 6 | = | z |$, sketch the locus of $P$.
\item Find the complex numbers $z$ which satisfy both $| z - 6 | = | z |$ and $| z - 3 - 4 \mathrm { i } | = 5$.

The transformation $T$ from the $z$-plane to the $w$-plane is given by $w = \frac { 30 } { z }$.
\item Show that $T$ maps $| z - 6 | = | z |$ onto a circle in the $w$-plane and give the cartesian equation of this circle.
\end{enumerate}

\hfill \mbox{\textit{Edexcel FP2 2010 Q6 [10]}}