Let's break down and simplify the given expression step by step:

Expression:
$(-3x^2 + 3x \cdot (-8)) + (6x^2 - 4x)$

Step 1: Simplify each term inside the parentheses.

1. The first part is:
   $-3x^2 + 3x \cdot (-8) = -3x^2 - 24x$

2. The second part is:
   $6x^2 - 4x$

Step 2: Combine like terms.

Now, combine the two parts:

$(-3x^2 - 24x) + (6x^2 - 4x)$

Combine the $x^2$ terms and the $x$ terms:

$(-3x^2 + 6x^2) + (-24x - 4x) = 3x^2 - 28x$

Final Answer:

$3x^2 - 28x$

Would you like more details, or do you have any questions?

Here are five related questions:

1. How do you factor the expression $3x^2 - 28x$?
2. What is the solution to $3x^2 - 28x = 0$?
3. How does this simplification change for different coefficients?
4. What happens if we include a constant term in this expression?
5. How does the quadratic term affect the shape of the graph?

Tip: Always combine like terms carefully to simplify complex expressions efficiently.