Question

add.
$(9y^2 + y - 7) + (9y^2 - y - 4)$
$(9y^2 + y - 7) + (9y^2 - y - 4) = \square$
(simplify your answer.)

Explanation:

Step1: Remove parentheses

$9y^2 + y - 7 + 9y^2 - y - 4$

Step2: Combine like $y^2$ terms

$9y^2 + 9y^2 = 18y^2$

Step3: Combine like $y$ terms

$y - y = 0$

Step4: Combine constant terms

$-7 - 4 = -11$

Step5: Sum all simplified terms

$18y^2 + 0 - 11$

Answer:

$18y^2 - 11$