The expression you provided is:

$-6i(i - 5)$

Let's simplify it step by step:

1. Distribute the $-6i$ across the terms inside the parentheses:

$-6i(i - 5) = (-6i \cdot i) + (-6i \cdot (-5))$

2. Simplify each term:

   • $-6i \cdot i = -6i^2$ (since $i \cdot i = i^2$)
   • $-6i \cdot (-5) = 30i$

3. Recall that $i^2 = -1$, so:

$-6i^2 = -6(-1) = 6$

4. Now, substitute this into the expression:

$6 + 30i$

So, the simplified form of $-6i(i - 5)$ is:

$6 + 30i$

This is a complex number in the form $a + bi$, where $a = 6$ and $b = 30$.

Would you like more details or have any questions?

Here are 5 follow-up questions for further exploration:

1. What happens when you multiply two complex numbers together?
2. How does this result relate to the geometric interpretation of complex numbers?
3. Can you factor complex numbers similarly to how we factor real numbers?
4. How would you divide complex numbers?
5. What is the significance of the imaginary unit $i$ in electrical engineering?

Tip: When working with complex numbers, remember that $i^2 = -1$ is a key property that simplifies many expressions.