1. Day 14 – September 13th and 14th Objective:
Look at Test

2. A relation is a set of pairs of input and output values.

3. Function
A function is a relation in where every input leads to a unique output.
What does this mean????

4. Make a mapping diagram for each relation and then determine if the relation is a function
b. {(–1, 5), (0, 3), (2, 3), (3, –1)}
c. {(0, 4), (–2, 3), (–1, 3), (–2, 2), (1, –3)}

5. Vertical Line Test
Graphing a relation gives us an easy way to tell if it is a function. We will use the vertical-line test to determine if each of the following graphs represents a function.

6. Direct Variation
A linear equation of the form y = kx, where k = 0, represents direct variation.
We call k the _____________________.
Solve y = kx for k.

7. How do we check for Direct Variaton?x y 1 2 3 6 4 8 x y 1 5 3 15 4 20

8. For the following functions, determine if y varies directly with x
For the following functions, determine if y varies directly with x. If so, find the constant of variation and write the equation. x y -6 -2 3 1 12 4 x y 1 4 2 7 5 16
If we graphed the equation we wrote for number 1, what would it look like?

9. Writing a Direct Variation Equation
A dripping faucet wastes one cup of water if it drips for three minutes. The amount of water wasted varies directly with the amount of time the faucet drips. a.) Find the constant of variation, and write an equation to model the situation. b. How long would it take to waste 4½ cups of water?

10. Proportions
You can also use a proportion to solve in direct variation situations.
1) Suppose y varies directly with x, and if y = 4 then x = 3
Find y when x = 6.
2) Suppose y varies directly with x, and if y = 10 then x = -3.
Find y when x = 2.

11. Standard Form of a Linear Line
Standard Form: Ax + By = C ; where A,B, and C are whole numbers. Write the equation in standard form with integer coefficients.

12. X and Y intercepts
Finding x and y intercepts.
3x + 5y = 15