Answer:
-y² - 3y + 21
Step-by-step explanation:
Our expression here is 21 - y(y + 3).
Let's focus on the parentheses part: y(y + 3). This is basically the same as writing y * (y + 3). We need to distribute out this parentheses. To do this, we multiply the outside term (y) by each of the inside terms (y and 3) and add those together:
y * (y + 3) = y * y + y * 3 = y² + 3y
Now, let's put that back into the original problem:
21 - y(y + 3)
21 - (y² + 3y)
21 - y² - 3y
The answer is thus -y² - 3y + 21.
~ an aesthetics lover
