Answer: 13.
- A 5
- B 9
- C 13
- D 6
Correct answer: C. 13
Explanation: (a+ib)(a-ib) = a<sup>2</sup> + b<sup>2.</sup> Here (3+2i)(3-2i) = 9 + 4 = 13.
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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