To simplify the expression \( 4x^2 - 3x^2 + 5x - 24 \), we first combine like terms:
\[ 4x^2 - 3x^2 = 1x^2 \]
So the expression simplifies to:
\[ x^2 + 5x - 24 \]
Now we need to factor \( x^2 + 5x - 24 \). We are looking for two numbers that multiply to \(-24\) and add to \(5\). The numbers \(8\) and \(-3\) fit these conditions:
\[ x^2 + 5x - 24 = (x + 8)(x - 3) \]
Now, let's compare this result to the options provided:
- \( (x + 6)(x - 4) \) → Expands to \( x^2 + 2x - 24 \) (not the same).
- \( 2(x - 12) \) → Expands to \( 2x - 24 \) (not the same).
- \( 4x(x - 6) \) → Expands to \( 4x^2 - 24x \) (not the same).
- \( (x + 8)(x - 3) \) → We found this matches our factorization.
Therefore, the expression \( 4x^2 - 3x^2 + 5x - 24 \) simplifies to the same expression as option 4:
\[ \boxed{(x + 8)(x - 3)} \]