It is given that z = -√3 + i.
- (a)Express z² in the form re^(iθ), where r > 0 and -π < θ ≤ π.[3]
- (b)The complex number ω is such that z²ω is real and |z²/ω³| = 12. Find the two possible values of ω, giving your answers in the form Re^(iα), where R > 0 and -π < α ≤ π.[3]
Mark scheme
Marking points from the official mark scheme (Feb/Mar 2024). The mark or mark type is shown in brackets.
- [B1] Obtain r = 4
- [M1] Correct method for the argument
- [A1] Obtain θ = -π/3
- [M1] Use of α + their θ = 0 or α + their θ = -π or α + their θ = π
- [M1] Use of R = their r / 12
- [A1] Obtain (1/3)¹/³e^(iπ/3) and (1/3)¹/³e^(-i2π/3)
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