Halloween Warm-Up

• Paul has two dozen Halloween cookies. He will eat three cookies on Sunday. On every day that follows, he will eat a number of cookies that is one greater than the day before. On what day will he find that he doesn’t have enough cookies to follow this procedure?

Answer

• Thursday

• Sun -3 Mon- 4 Tues- 5 Wed -6

18 cookies eaten

24 -18 = 6 cookies left over, but on Thursday he needs to eat 7 cookies to continue his pattern.

Solving Two- Step Equations

Lesson 4-4

Rules to Remember

• When solving an equation, the goal is to get the variable by itself.

• Addition and Subtraction are inverse operations. (opposites)

• Multiplication and Division are inverse operations. (opposites)

Don’t Forget

• The equation is like a balance scale. Whatever you do to one side of the equation must be done to the other side of the equation.

How to solve two-step equations

• “Undo” the operations in the reverse order of the order of operations.

• You are using the work back-words strategy

• In order of operations we do multiplication or division first, then addition and subtraction. When solving an equation we do the opposite!

Integer Rules to Remember

• Adding Integers

1. Same sign= add and keep the sign

2. Different sign = subtract and keep the sign of the larger number

• Subtracting Integers

1. Keep, Change, Change

2. Follow the rules for addition• Multiplying and Dividing Integers

1. Same Sign = Positive Answer

2. Different Sign = Negative Answer

Let’s Try One…

• 3x + 2 = 23

- 2 -2

21

3x = 21

3 3

x = 7

The problem contains addition and multiplication. Which one do we undo 1st?

Another Example

• -2y – 7 = 3

+7 +7

10

-2y = 10

-2 -2

y = -5

The problem contains subtraction and multiplication. Which one do we undo 1st?

Last Example

• -3c + 9 = 3

-9 -9

-6

-3c = -6

-3 -3

c = 2

The problem contains addition and multiplication. Which one do we undo 1st?

Now it’s your turn

1. 5x + 4 = 19

2. 2t + 7 = -1

3. 6m + 1 = -23

4. -4w – 4 = 8

5. -7y + 3 = -25

6. 3t – 13 = 2

1. x = 3

2. t = -4

3. m = -4

4. w = -3

5. y = 4

6. t = 5

Homework

• Complete Lesson 4-4 # 2-24 evens