Question

Find the square of the imaginary number 3i:

A) -3
B) -9
C) -27
D) -81

Answer 1

The square of the imaginary number 3i is calculated by squaring both the coefficient and imaginary unit, resulting in -9.

Step-by-step explanation:

To find the square of the imaginary number 3i, we remember that i is defined as the square root of -1. Therefore, i2 is -1. We apply the exponent to both the numerical coefficient and the imaginary unit, giving us:

(3i)2 = 32 × i2 = 9 × -1

Thus, the square of 3i is -9, which matches option B).