To simplify the expression \((4x^4 + 4x^3 - 1) - (5x^2 - 9x + 6)\), you can start by distributing the negative sign across the second set of parentheses:
\[ = 4x^4 + 4x^3 - 1 - 5x^2 + 9x - 6 \]
Now, combine like terms:
- The term \(4x^4\) has no like terms, so it remains as \(4x^4\).
- The term \(4x^3\) also has no like terms, so it remains as \(4x^3\).
- The term \(-5x^2\) has no like terms, so it stays as \(-5x^2\).
- The term \(9x\) has no like terms, so it remains as \(9x\).
- Combine the constant terms: \(-1 - 6 = -7\).
Putting it all together, the simplified expression is:
\[ 4x^4 + 4x^3 - 5x^2 + 9x - 7 \]