The given expression is:

$(-10x^2 + 4) + (-9x - 6)$

To perform the operation, we combine like terms.

Step 1: Combine the $x^2$ terms

There is only one $x^2$ term: $-10x^2$.

Step 2: Combine the $x$ terms

There is only one $x$ term: $-9x$.

Step 3: Combine the constant terms

We have $+4$ and $-6$. Adding them together:

$4 - 6 = -2$

Final expression:

$-10x^2 - 9x - 2$

This is the simplified result.

Do you want further details or have any questions?

Here are 5 related questions:

1. How do you add or subtract polynomials?
2. What are like terms, and how do you identify them?
3. How do you simplify an expression with multiple variables?
4. Can you explain how to distribute signs in a polynomial?
5. How do you factor polynomials after simplification?

Tip: When simplifying polynomials, always look for like terms (same variable and same exponent) to combine them efficiently!