Write in interval notation: x≤−1.5.

 (-∞, 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]

for ex: the reciprocal of 3/4 is 4/3. it is the opposite.

reciprocal definition:

a mathematical expression or function so related to another that their product is one; the quantity obtained by dividing the number one by a given quantity.

false

step-by-step explanation: