Simplifying the Expression: (y² - 4y + 9) - (3y² - 6y - 9)
This expression involves subtracting one trinomial from another. Let's break down the steps to simplify it:
1. Distribute the Negative Sign:
The minus sign in front of the second parenthesis means we multiply each term inside the parenthesis by -1:
(y² - 4y + 9) + (-1)(3y² - 6y - 9)
This becomes:
y² - 4y + 9 - 3y² + 6y + 9
2. Combine Like Terms:
Identify the terms with the same variable and exponent and group them together.
y² - 3y² - 4y + 6y + 9 + 9
3. Simplify:
Perform the addition and subtraction for each group of like terms:
-2y² + 2y + 18
Therefore, the simplified form of the expression (y² - 4y + 9) - (3y² - 6y - 9) is -2y² + 2y + 18.