Final answer:
To solve the absolute value inequality 3x-9+12>=21, isolate the absolute value expression and solve for x.
Step-by-step explanation:
To solve the absolute value inequality 3x-9+12>=21, we can start by isolating the absolute value expression. Subtracting 12 from both sides gives us 3x-9 >= 9. Next, we can isolate the absolute value by adding 9 to both sides, giving 3x >= 18. Dividing both sides by 3 gives us x >= 6. Therefore, the solution to the absolute value inequality 3x-9+12>=21 is x >= 6.