Answer :
Given the following expression:
[tex](-7x^2-4)+(-7^{}x^2-6x-2)[/tex]since we dont have any sign on the left of the first summand and there is a plus sign next to the second summand, we can write all the terms without the parenthesis:
[tex](-7x^2-4)+(-7x^2-6x-2)=-7x^2-4-7x^2-6x-2[/tex]then, notice that we only have as similar terms -7x^2, then, we can simplify:
[tex]-7x^2-4-7x^2-6x-2=-14x^2-6x-6[/tex]therefore, the final result is -14x^2-6x-6