Date | November 2020 | Marks available | 5 | Reference code | 20N.1.AHL.TZ0.H_4 |
Level | Additional Higher Level | Paper | Paper 1 (without calculator) | Time zone | Time zone 0 |
Command term | Find | Question number | H_4 | Adapted from | N/A |
Question
Consider the equation 2z3-z*=i, where z=x+iy and x, y∈ℝ.
Find the value of x and the value of y.
Markscheme
* This question is from an exam for a previous syllabus, and may contain minor differences in marking or structure.
substituting z=x+iy and z*=x-iy M1
2(x+iy)3-(x-iy)=i
2x+2iy=-y+i(3-x)
equate real and imaginary: M1
y=-2x AND 2y=3-x A1
Note: If they multiply top and bottom by the conjugate, the equations 6x-2x2+2y2=0 and 6y-4xy=(3-x)2+y2 may be seen. Allow for A1.
solving simultaneously:
x=-1, y=2 (z=-1+2i) A1A1
[5 marks]
Examiners report
[N/A]