Final answer:
To find an expression for 3C - 3D, where C = q² - 2 + q and D = 3q² + 2q, we calculate 3C and -3D separately and then combine them to get the final expression in standard form: -6q² - 6.
Step-by-step explanation:
The student is asking to find an expression for 3C - 3D where C is defined as C = q² - 2 + q and D is defined as D = 3q² + 2q. To simplify this expression, let's first multiply both C and D by 3.
First, for 3C we have:
- 3C = 3(q² - 2 + q)
- 3C = 3q² - 6 + 3q
And for -3D, we have:
- -3D = -3(3q² + 2q)
- -3D = -9q² - 6q
Now, combining the expressions for 3C and -3D:
- 3C - 3D = (3q² - 6 + 3q) - (9q² + 6q)
- 3C - 3D = 3q² - 9q² - 6 + 6q - 6q
- 3C - 3D = -6q² - 6
Therefore, the expression in standard form for 3C - 3D is -6q² - 6.