Question

If i^2 = −1 and x = i + 9, which is the result of squaring x?

Answer 1

80 + 18i

Explanation:

i² = -1

x = i + 9

x² = (i + 9)²

Applying; (a + b)² = a² + 2ab + b² concept,

x² = i² + 18i + 81

We know that i² = -1

So x² = -1 + 18i + 81

x² = 81 - 1 + 18i = 80 + 18i