1. Warm Up
Problem of the Day
Lesson Presentation
Lesson Quizzes

2. Evaluate each expression for the given value of the variable.
Warm Up
Evaluate each expression for the given value of the variable.
1. 4x – 1 for x = 2
2. 7y + 3 for y = 5
3. x + 2 for x = –6
4. 8y – 3 for y = –2 7 38 1 2 __ –1
–19

3. Problem of the Day
These are rits: 24042, 383, and These are not rits: 39239, 28, and Which of these are rits: 39883, 4040, and 101? Why?
101 is a rit because it is the same forward and backward

4. Learn to use data in a table to write an equation for a function and to use the equation to find a missing value.

5. Vocabulary
function
input
output

6. A function is a rule that relates two quantities so that each input value corresponds exactly to one output value.

7. Additional Example 1: Writing Equations from Function Tables
Write an equation for a function that gives the values in the table. Use the equation to find the value of y for the indicated value of x. 25 22 19 16 13 y 10 7 6 5 4 3 x
Compare x and y to find a pattern.
y is 3 times x plus 4.
Use the pattern to write an equation.
y = 3x + 4
Substitute 10 for x.
y = 3(10) + 4
Use your function rule to find y when x = 10.
y = = 34

8. When all the y-values are greater than the corresponding x-values, use addition and/or multiplication in your equation.
Helpful Hint

9. Check It Out: Example 1
Write an equation for a function that gives the values in the table. Use the equation to find the value of y for the indicated value of x. 18 16 14 12 10 y 7 6 5 4 3 x
Compare x and y to find a pattern.
y is 2 times x + 4.
Use the pattern to write an equation.
y = 2x + 4
Substitute 10 for x.
y = 2(10) + 4
Use your function rule to find y when x = 10.
y = = 24

10. You can write equations for functions that are described in words.

11. Additional Example 2: Translating Words into Math
Write an equation for the function. Tell what each variable you use represents.
The height of a painting is 7 times its width.
Choose variables for the equation.
h = height of painting
w = width of painting
Write an equation.
h = 7w

12. Check It Out: Example 2
Write an equation for the function. Tell what each variable you use represents.
The height of a mirror is 4 times its width.
Choose variables for the equation.
h = height of mirror
w = width of mirror
Write an equation.
h = 4w

13. Understand the Problem
Additional Example 3: Problem Solving Application
The school choir tracked the number of tickets sold and the total amount of money received. They sold each ticket for the same price. They received $80 for 20 tickets, $88 for 22 tickets, and $108 for 27 tickets. Write an equation for the function. 1
Understand the Problem
The answer will be an equation that describes the relationship between the number of tickets sold and the money received.

14. 2
Make a Plan
You can make a table to display the data.
Solve 3
Let t be the number of tickets. Let m be the amount of money received.
108 88 80 m 27 22 20 t
Compare t and m.
m is equal to 4 times t.
Write an equation.
m = 4t

15. Look Back 4
Substitute the t and m values in the table to check that they are solutions of the equation m = 4t.
m = 4t (20, 80)‏
m = 4t (22, 88)‏
m = 4t (27, 108)‏
80 = 4 • 20 ?
88 = 4 • 22 ?
108 = 4 • 27 ?
80 = 80 ?
88 = 88 ?
108 = 108 ?

16. Understand the Problem
Check It Out: Example 3
The school theater tracked the number of tickets sold and the total amount of money received. They sold each ticket for the same price. They received $45 for 15 tickets, $63 for 21 tickets, and $90 for 30 tickets. Write an equation for the function. 1
Understand the Problem
The answer will be an equation that describes the relationship between the number of tickets sold and the money received.

17. 2
Make a Plan
You can make a table to display the data.
Solve 3
Let t be the number of tickets. Let m be the amount of money received. 90 63 45 m 30 21 15 t
Compare t and m.
m is equal to 3 times t.
Write an equation.
m = 3t

18. Look Back 4
Substitute the t and m values in the table to check that they are solutions of the equation m = 3t.
m = 3t (15, 45)‏
m = 3t (21, 63)‏
m = 3t (30, 90)‏
45 = 3 • 15 ?
63 = 3 • 21 ?
90 = 3 • 30 ?
45 = 45 ?
63 = 63 ?
90 = 90 ?

19. Lesson Quiz for Student Response Systems
Lesson Quizzes
Standard Lesson Quiz
Lesson Quiz for Student Response Systems 19 19

20. Lesson Quiz
1. Write an equation for a function that gives the values in the table below. Use the equation to find the value for y for the indicated value of x.
2. Write an equation for the function. Tell what each variable you use represents. The height of a round can is 2 times its radius. 15 9 3 y 7 5 1 x
y = 3x; 21
h = 2r, where h is the height and r is the radius

21. Lesson Quiz for Student Response Systems
1. Identify an equation for a function that gives the values in the table below. Then, use the equation to find the value for y for the indicated value of x.
A. y = 4x + 8; 21
B. y = 7x – 7; 21
C. y = 4x + 8; 28
D. y = 7x – 7; 28 21 21

22. Lesson Quiz for Student Response Systems
2. Identify an equation for the function. Tell what each variable you use represents.
The width of a swimming pool is twice its depth.
A. w = 2d, where d is the width and w is the depth
B , where w is the width and d is the depth
C. w = 2d, where w is the width and d is the depth
D. , where d is the width and w is the depth 22 22