Answer: 3.
- A 6
- B -3
- C 12
- D 3
Correct answer: D. 3
Explanation: z - z-bar = (a+ib)-(a-ib) = 2ib = 6i. So b = 3. Im(z) = 3.
A complex number z = a+ib is plotted as a point (or vector from the origin) on the Argand plane, with the real part along the horizontal axis and the imaginary part along the vertical; its modulus |z| is the vector's length, and its argument θ is the angle from the positive real axis.
Concept context
Complex numbers in a+ib form, modulus, argument, polar form, cube roots of unity, and quadratic equations with complex roots
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