Chapter 8 – Functions and Graphing

8.2 – Linear Equations in Two Variables

Did you know that crickets can tell the temperature?Chirps in

15 seconds T = c+ 40

Temperature

(°F)

21

23

31

50

47

•Write the relation as a set of coordinate points.

•What is the domain of the relation?

•What is the range of the relation?

10 20 30 40 50 60

10

20

30

40

50

60

70

80

90

100

Chirps in 15 secondsTe

mp

era

ture

Staircase Towers

What expression can we use to represent the nth tower?

1 32 4

2n + 1B =

tower numbernumber of blocks

Let’s use the pattern to make a table of values.

n B = 2n + 1 B (n, B)

1 B = 2(1) + 1 3 (1, 3)

2 B = 2(2) + 1 5

3 B = 2(3) + 1

4

5

6

7

8

A linear equation in two variables is an equation in which the variables appear in separate terms and neither variable contains an exponent other than the number 1.

Use an x-y table to find solutions to linear relations or equations.

Find four solutions of the equation. Then write the solutions as ordered pairs.

y = x + 1x y = x + 1 y (x, y)

Find four solutions for y = 4x – 3. Then graph y = 4x – 3.

x y = 4x – 3 y

Find four solutions for x + y = 10. Then graph x + y = 10.

x y

Use a table to graph y = -2.

x y

Questions?

• Homework:

8.2 pg 378 #6-48

(div by 3)