Simplify the following expression: 3a - 6 + a2 - 3(a2 + 8)

Simplifying the given expression:

3a - 6 + a^2 - 3(a^2 + 8)

First simplify within the parentheses:

3a - 6 + a^2 - 3a^2 - 24

Next, combine like terms:

(3a - 3a^2) + (a^2 - 6 - 24)

This simplifies to:

-3a^2 + a^2 - 30

Combining like terms further:

(a^2 - 3a^2) - 30

This can be written as:

-2a^2 - 30

Therefore, the simplified expression is -2a^2 - 30.

To simplify the expression 3a - 6 + a^2 - 3(a^2 + 8), we can follow these steps:

1. Distribute the -3 to the terms inside the parentheses:
3a - 6 + a^2 - 3a^2 - 24

2. Combine like terms:
(3a - 3a^2) + (a^2 - 6 - 24)

3. Simplify the terms:
-3a^2 + 3a + a^2 - 30

4. Combine like terms:
-2a^2 + 3a - 30

Therefore, the simplified expression is -2a^2 + 3a - 30.