Multiply and simplify the product. -12i × 3i. Select the product. 
36, -36, 36i, -36i

Solution:

Given, -12i × 3i

⇒ (-36) × i²

We have i = √(-1) ⇒ i² = -1

∴ (-36) × i²

= (-36) × (-1)

= 36

Answer is (a).

Here, i is called iota which stands for √-1

And it exists such that i² = -1, i³ = -i , i⁴ = 1 and in fact i⁴ⁿ = 1 for n ∊ Z

Also we may note when we have four consecutive powers of i the sum is always zero.

That is i¹⁰⁰ + i¹⁰¹ + i¹⁰² + i¹⁰³ = 0

Multiply and simplify the product. -12i × 3i. Select the product.

Summary:

The product of -12i × 3i is 36. Here, i is called iota which stands for √-1