2. If the difference between the maximum and minimum elements of the real number set $\{1,2,3, x\}$ equals the sum of all elements in the set, then the value of $x$ is $\qquad$ ـ.
Answer: $-\frac{3}{2}$.
Solution: Suppose $x \geq 0$, then the difference between the maximum and minimum elements does not exceed $\max \{3, x\}$, while the sum of all elements is greater than $\max \{3, x\}$, which does not meet the condition. Therefore, $x<0$, meaning $x$ is the minimum element. Thus, $3-x=6+x$, solving for $x$ gives $x=-\frac{3}{2}$.