Answer:
I'm assuming the 2 after 9t and -2t means squared.
7t² + 12t + 4
Explanation:
To simplify the expression we should combine like terms. Like terms are terms with same variables and powers.
Let's start with 9t² and -2t² since they have the same variable and power of t². To combine them we should add them together which would be: 9t² + (-2t²) = 9t² - 2t² = 7t²
Next we can combine 7t and 5t since they have the same variable and power of t. 7t + 5t = 12t
4 doesn't have any like terms so we leave it as it is.
Lastly we add all of our terms: 7t² + 12t + 4