# Functions and graphs

> Grade 9: function input and output, gradient and y-intercept from y = mx + c, parallel lines have the same gradient, shape of a quadratic graph, distance-time graphs.

Source: https://olyclass.com/library/math-g9-functions-graphs-en/

- Subject: Math
- Level: Grade 9
- Practice: 16
- Play it free on one screen (projector, TV or whiteboard): https://olyclass.com/library?play=math-g9-functions-graphs-en
- Copy and edit it: https://olyclass.com/library?copy=math-g9-functions-graphs-en
- Games it plays well in: [Mini Golf](https://olyclass.com/classroom-games/mini-golf/), [Ladder Climb](https://olyclass.com/classroom-games/ladder-climb/), [Paper Race](https://olyclass.com/classroom-games/paper-race/), [Three in a Row](https://olyclass.com/classroom-games/three-in-a-row/)

## Questions

1. A function is f(x) = 3x + 2. What is the output when the input is 4? (11 / 12 / 14 / 24)
   Answer: 14
2. A function machine doubles the input, then subtracts 5. Input 9 gives which output? (13 / 18 / 4 / 8)
   Answer: 13
3. For f(x) = x² − 1, what is f(5)?
   Answer: 24
4. A function machine adds 3 and outputs 10. What was the input? (13 / 3 / 30 / 7)
   Answer: 7
5. What is the gradient of the line y = 5x − 2? (-2 / -5 / 2 / 5)
   Answer: 5
6. What is the y-intercept of the line y = 2x + 7? (-7 / 2 / 7 / 9)
   Answer: 7
7. Where does the line y = −3x + 4 cross the y-axis? Give the y-value.
   Answer: 4
8. The lines y = 2x + 1 and y = 2x − 5 are parallel.
   Answer: True
9. Which line is parallel to y = 4x + 3? (y = 3x + 4 / y = 4x − 1 / y = x + 3 / y = −4x + 3)
   Answer: y = 4x − 1
10. The lines y = 3x + 2 and y = 2x + 3 are parallel.
   Answer: False
11. What is the shape of the graph of y = x²? (A U-shaped curve (parabola) / A V-shaped pair of lines / A circle / A straight line)
   Answer: A U-shaped curve (parabola)
12. The graph of y = −x² opens in which direction? (Downwards / To the left / To the right / Upwards)
   Answer: Downwards
13. The graph of a quadratic function such as y = x² + 2x is a straight line.
   Answer: False
14. On a distance-time graph, what does a horizontal line show? (Constant speed / Returning to the start / Speeding up / The object is not moving)
   Answer: The object is not moving
15. A distance-time graph goes from (0 h, 0 km) to (2 h, 30 km) in a straight line. Speed? (15 km/h / 2 km/h / 30 km/h / 60 km/h)
   Answer: 15 km/h
16. On a distance-time graph, a steeper straight line means a greater what?
   Answer: Speed