To simplify the given expression $(2x^2 - x - 1) - (6x + 4)$, follow these steps:

1. Distribute the negative sign to the terms inside the second set of parentheses: $= 2x^2 - x - 1 - 6x - 4$

2. Combine like terms:

   • $2x^2$ has no like terms, so it stays as $2x^2$.
   • Combine the $x$-terms: $-x - 6x = -7x$.
   • Combine the constants: $-1 - 4 = -5$.

Thus, the simplified expression is: $2x^2 - 7x - 5$

Would you like more details or have any questions?

Here are 5 related questions:

1. How do you factor quadratic expressions like $2x^2 - 7x - 5$?
2. What are the common steps to solve a quadratic equation?
3. How do you use the quadratic formula for equations like $2x^2 - 7x - 5 = 0$?
4. What is the difference between combining like terms and distributing?
5. How do you solve systems of equations that involve quadratic expressions?

Tip: Always check your work for combining like terms and distributing to avoid sign errors.