1. 2.4 variables and equations September 12, 2011
Distribute. Simplify
Bellwork
1. -3(x - 7) 3. -3(x - 7)+ 2x
2. (4 + c)8 4. 4 + 8c - 5
Objective - classify types of equations
HW pg. 1­35 odds 1

2. 2.4 variables and equations September 12, 2011
equation - mathematical sentence with an equal sign
Types of equations we'll see:
9 + 2 = 11 numerical expression = numerical expression
x + 7 = 37 variable expression = numerical expression
a + (-3) = 2a + 5 variable expression = variable expression
HW pg. 1­35 odds 2

3. 2.4 variables and equations September 12, 2011
open sentence - equation with one or more variables
State whether each equation is true or false, and open sentence.
6 + 12 = 18
6=4+3
6 = - 3 + 5y
HW pg. 1­35 odds 3

4. 2.4 variables and equations September 12, 2011
Write an equation for
Nine times the opposite of five is forty-five.
Is this T, F, or open?
HW pg. 1­35 odds 4

5. 2.4 variables and equations September 12, 2011
Write an equation for
twenty minus x is three
Is this T, F, or open?
HW pg. 1­35 odds 5

6. 2.4 variables and equations September 12, 2011
solution of an equation - a value of a variable that makes an equation true.
Is 30 a solution of the equation 170 + x = 200?
HW pg. 1­35 odds 6

7. 2.4 variables and equations September 12, 2011
Is the given number a solution of the equation?
8 + t = 2t; 1
HW pg. 1­35 odds 7

8. 2.4 variables and equations September 12, 2011
A diver's equipment weighs 35 lb.
The diver plus the equipment weighs 165 lb.
Can the diver's weight be 200 lb?
HW pg. 1­35 odds 8

9. 2.4 variables and equations September 12, 2011
HW: pg 82 #1-35 odds
HW pg. 1­35 odds 9

10. 2.4 variables and equations September 12, 2011
Page 82 # 2 ­ 22 even, 27 ­ 40 all, 51 ­ 53 all
2 open 31 true, 12 = 12
4 open 32 open
6 open 33 (­20)(9) = ­11, false; ­180 = ­ 11
8 open 34 15 + n = 60; open
10 4(­5) = ­20, true, ­20 = ­20
12 yes 35 48 ÷ 12 = 3; false 4 ≠ 3
14 yes 36 No; an expression is not a sentence
16 no 37 yes, ­9 = ­9
18 no 38 no 14 ≠ 2
20 yes 39 no ­ 6 ≠ 6
22 850 + x = 1,200 40 yes; 2 = 2
27 true, 18 = 18 51 16
28 false, 48 = 108
52 0
29 open
30 ture, 10 = 10 53 8
HW pg. 1­35 odds 10

11. 2.4 variables and equations September 12, 2011
P 78 # 1­ 3, 11 ­ 26 all, 32, 35
coef, like, constant
1 3, 5 none ­3
2 2 none ­7
3 4, ­7, 3 4x, ­7x, 3x none
11 13a
12 13a
23 ­60 + 54k
13 ­b 24 ­4r + 3
14 6w 25 ­5a ­ 12
15 8r ­ 5 26 3
16 9a ­ 3 32 4p + 10 + 3, or 4p + 13
17 5g + 15 35 The variables are not separated
18 5z + 8y
19 ­m + 4d
by a plus or minus sign
20 3t + 1
21 11z + 8y
22 4
HW pg. 1­35 odds 11