Choose the interval form of (4x+1\geq9).

Correct answer: ([2,\infty))

To change an inequality into interval form, first isolate the variable and then show whether the endpoint is included. Starting with 4x+1≥9, subtracting 1 from both sides gives 4x≥8. Dividing by the positive number 4 does not reverse the inequality, so x≥2. Thus, all real numbers from 2 onward are included.

The interval for x≥2 is [2,∞). The square bracket at 2 shows that 2 itself is allowed because equality is included. Infinity always uses a parenthesis because it is not an actual number that can be included as an endpoint. Therefore, option A is correct. Option B would represent x>2 and would incorrectly exclude 2.