Answer:
3d²
Step-by-step explanation:
Hello!
To simplify, we combine the like terms by adding them.
Like terms are terms with the same variable and degree. A degree is a power to which the term is raised. Like terms can have numerical coefficients. For example, a coefficient of 4 to x² would mean 4 times x².
We can see that the variable d² is common throughout the three terms, meaning they are like terms. We can simply add and subtract them.
The simplified form is 3d².