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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.

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

2x+iy3-x-iy=i

2x+2iy=-y+i3-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-x2+y2 may be seen. Allow for A1.


solving simultaneously:

x=-1, y=2  z=-1+2i      A1A1


[5 marks]

Examiners report

[N/A]

Syllabus sections

Topic 1—Number and algebra » AHL 1.12—Complex numbers – Cartesian form and Argand diag
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Topic 1—Number and algebra

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