Answer :

To solve the equation [tex]\( |x+3| = 12 \)[/tex], we need to consider two separate cases because the absolute value operation can yield two different equations: one for the positive scenario and one for the negative scenario.

Case 1: [tex]\( x+3 = 12 \)[/tex]
- Solve for [tex]\( x \)[/tex]:
[tex]\[ x + 3 = 12 \\ x = 12 - 3 \\ x = 9 \][/tex]

Case 2: [tex]\( x+3 = -12 \)[/tex]
- Solve for [tex]\( x \)[/tex]:
[tex]\[ x + 3 = -12 \\ x = -12 - 3 \\ x = -15 \][/tex]

So, the solutions to the equation [tex]\( |x+3| = 12 \)[/tex] are [tex]\( x = 9 \)[/tex] and [tex]\( x = -15 \)[/tex].

Hence, the correct answer is:
D. [tex]\( x = 9, -15 \)[/tex]