The problem asks to multiply:

$-3i(2 + 4i)$

We will distribute $-3i$ to each term inside the parentheses.

1. First, multiply $-3i$ by 2:

$-3i \times 2 = -6i$

2. Next, multiply $-3i$ by $4i$:

$-3i \times 4i = -12i^2$

Since $i^2 = -1$, this simplifies to:

$-12i^2 = -12(-1) = 12$

Now, combine the real and imaginary parts:

$12 - 6i$

Thus, the answer in standard form is:

$12 - 6i$

Would you like more details or have any questions?

Here are 5 related questions to practice:

1. Multiply $5i(3 + 2i)$.
2. Simplify $(2 + 3i)(1 - 4i)$.
3. Find the product of $-i(4 + 7i)$.
4. Expand $(2 - 3i)^2$.
5. Divide $\frac{4 + 2i}{1 - i}$ and simplify.

Tip: Remember that $i^2 = -1$ is key to simplifying complex number products!