Question

simplify.
$-4x^2 - 9x^2$

Explanation:

Step1: Identify like terms

Both terms have $x^2$, so they are like terms.

Step2: Combine coefficients

Add the numerical coefficients: $-4 - 9 = -13$
Attach the common variable part $x^2$ to the result.

Answer:

$-13x^2$