Answer: 2i.
- A 1+2i
- B 2i
- C 2+2i
- D 1-2i
Correct answer: B. 2i
Explanation: (1+i)<sup>2</sup> = 1 + 2i + i<sup>2</sup> = 1 + 2i - 1 = 2i.
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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