The problem asks us to express the set $\{x : x \in R, 1 \le x \le 2\}$ as an interval. In other words, we want to represent all real numbers $x$ such that $x$ is greater than or equal to 1 and less than or equal to 2, using interval notation.

1. Problem Description

The problem asks us to express the set $\{x : x \in R, 1 \le x \le 2\}$ as an interval. In other words, we want to represent all real numbers $x$ such that $x$ is greater than or equal to 1 and less than or equal to 2, using interval notation.

2. Solution Steps

Since the set includes all real numbers $x$ such that $1 \le x \le 2$, and the inequality signs are $\le$ (less than or equal to), the interval will include the endpoints 1 and

2. Therefore, we use square brackets to indicate that the endpoints are included.

The interval notation will be $[1, 2]$.

3. Final Answer

$[1, 2]$