To determine the pair of equivalent expressions, we will simplify each option:
A. \( 3x + 2x \) simplifies to \( 5x \).
\( x^2(3 + 2) \) simplifies to \( 5x^2 \).
They are not equivalent.
B. \( 2x + 2 \) cannot be simplified further.
\( 2(x + 2) \) simplifies to \( 2x + 4 \).
They are not equivalent.
C. \( 2(x + 3) \) simplifies to \( 2x + 6 \).
Therefore, \( 2(x + 3) \) and \( 2x + 6 \) are equivalent.
D. \( -3(x + 2) \) simplifies to \( -3x - 6 \).
\( -3x - 3 \) does not equal \( -3x - 6 \).
They are not equivalent.
The only pair of equivalent expressions is:
C. \( 2(x + 3) \) and \( 2x + 6 \).