Problem Solving with TwoStep Equations Objective Learn to

Problem Solving with Two-Step Equations Objective: Learn to use more than one inverse operation to solve an equation.

Warm -Up G + 12 = 25 6 T = 36 15 = W - 10 H = 12 5

Real life example… You want to join an internet music club: You pay $7 to join an Internet music club. You pay $2 for each song that you download. Your cost for joining and downloading some songs is $23. How many songs can you download? To solve we can do an equation: cost to join + cost per song x number of songs = total cost 7 + 2 x S = 23

When solving two step equations… When an equation involves two operations, you need to use inverse operations one at a time. The order of operations say you must multiply or divide and then add or subtract. So to “undo” and solve the equation you will do everything backwards. We will first “undo” any addition and subtraction. Then “undo” any multiplication or division.

Steps: 1. Write the equation. 2. First undo any addition or subtraction. 3. Cancel the opposites. 4. Bring down what you have left. 5. Then undo any multiplication or division. 6. Cancel the opposites. 7. Solve. 8. Write the answer. Just don’t forget!!! Whatever you do to one side of the equal sign, you must do to the other!! Example… 2 w + 3 = 9 2 w 2 w -3 -3 = 6 2 = 3

Now, going back to the example…. 7 + 2 S = -7 2 S = 2 S= 23 7 16 2 8 songs

Examples: 6 X – 3 = 33 Y - 6 = 10 4 10 = T + 9 66 14 = 6 H + 2

Homework: 1. 5 N + 35 = 90 2. K + 9 = 15 7 3. 4 H – 8 = 8 4. 3 P – 10 = 8 5. R - 12 = 5 3