1. The problem asks to write the inequality $x \geq 3$ in interval notation. 2. Interval notation expresses the set of all numbers that satisfy the inequality. 3. Since $x$ is greater than or equal to 3, the interval starts at 3 and extends to infinity. 4. The square bracket $[$ means that 3 is included (because of the \geq symbol). 5. Infinity $\infty$ is always represented with a parenthesis $)$ because it is not a number and cannot be included. 6. Therefore, the interval notation is $$[3, \infty)$$.