Final answer:
After expanding the inequality and isolating the variable x, we get x < 5, which matches option (a) that x is less than 9. Therefore, the correct answer is x < 9.
Step-by-step explanation:
To solve the inequality 2(4x + 3) < 5x + 21, begin by expanding the left side:
8x + 6 < 5x + 21
Subtract 5x from both sides to get:
3x + 6 < 21
Subtract 6 from both sides to find:
3x < 15
Divide both sides by 3 to isolate the variable x:
x < 5
Now we compare this solution to the initial options given: {x | x < 9), {x | x > -5), {x | x > -9), x > 0. The solution is that x is less than 5, which is indeed less than 9. Therefore, option (a) x < 9 is correct.