Which restriction would enable the function f(x) = x2+6x-9 to have an inverse function?

Having a hard time understanding this question (see attachment).

Which description is represented by a discrete graph? kiley bought a platter for $19 and several matching bowls that were $8 each. what is the total cost before tax? the temperature at 9 a. m. was 83° f and is heating up at an average rate of 6°f per hour. what is the temperature x hours later? juan ate an egg with 78 calories and some cereal with 110 calories per serving for breakfast. what is the total amount of calories he consumed? a bottle contained 2,000 ml of liquid and is being poured out at an average rate of 300 ml per second. how much liquid is left in the bottle after x seconds?

This graph shows which inequality? a ≤ –3 a > –3 a ≥ –3 a < –3