$(a) \;\{x:x \in R,-2 \leq x <6\} \\ (b) \;\{x:x \in R,-2 \leq x,x \leq 6\} \\ (c) \;\{x:x \in R,-2 < x <6\} \\ (d) \;\{x:x \in R,-2 < x \leq 6\}$</span>
