How is the solution of the inequality \(2\le 3x-1<11\) written in interval notation?

Correct answer: [1,4)

Adding 1 to all three parts of \(2\le 3x-1<11\) gives \(3\le 3x<12\). Dividing throughout by 3 gives \(1\le x<4\). Thus, 1 is included and is written with a square bracket, whereas 4 is excluded and is written with a round bracket. Therefore, the interval is \([1,4)\). Exam tip: use a square bracket for an included endpoint marked by \(\le\) or \(\ge\), and a round bracket for an excluded endpoint marked by \(<\) or \(>\).