Answer: (-∞, 1.5]
Step-by-step explanation:
Parenthesis ( ) are used when the number is NOT included. Infinity is not a real number (it is a concept) so you need to use a parenthesis for ± infinity.
Brackets [ ] are used when the number IS included. Since 1.5 uses the "or equal to" symbol, it is included so you must use the bracket.
Parenthesis for negative infinity and bracket for 1.5: (-∞, 1.5]
