Question

Why is (-3,6] a better answer than (-3,6)

Answer 1

(-3, 6) includes all numbers between -3 and 6 but it does not include -3 and 6.

when you put square parentheses you include the number on the edge

so if an anwser includes all numbers between -3 and 6 and the number 6 it's correct to write (-3,6]