3 6 Solving Equations Containing Integers Warm Up

3 -6 Solving Equations Containing Integers Warm Up Problem of the Day Lesson Presentation Course 2

3 -6 Solving Equations Containing Integers Warm Up Use mental math to find each solution. 1. 2. 3. 4. Course 2 7 + y = 15 x÷ 9=9 6 x = 24 x – 12 = 30 y=8 x = 81 x=4 x = 42

3 -6 Solving Equations Containing Integers Problem of the Day Zelda sold her wet suit to a friend for $156. She sold her tank, mask, and snorkel for $85 less than she sold her wet suit. She bought a used wet suit for $80 and a used tank, mask, and snorkel for $36. If she started with $0, how much money does she have left? $111 Course 2

3 -6 Solving Equations Containing Integers Learn to solve one-step equations with integers. Course 2

3 -6 Solving Equations Containing Integers When you are solving equations with integers, the goal is the same as with whole numbers— isolate the variable on one side of the equation. One way to isolate the variable is to add opposites. Recall that the sum of a number and its opposite is 0. Course 2 + + + 0 – – – 3 + (– 3) = 0 a + (–a) = 0

3 -6 Solving Equations Containing Integers Helpful Hint 3 + (– 3) = 0 3 is the opposite of – 3. Course 2

3 -6 Solving Equations Containing Integers Additional Example 1 A: Solving Addition and Subtraction Equations Solve. Check each answer. A. – 6 + x = – 7 +6 +6 x = – 1 Check – 6 + x = – 7 ? – 6 + (– 1) = – 7 ? – 7 = – 7 Course 2 Add 6 to both sides to isolate the variable. Substitute – 1 for x in the original equation. True. – 1 is the solution to – 6 + x = – 7.

3 -6 Solving Equations Containing Integers Additional Example 1 B: Solving Addition and Subtraction Equations Solve. Check the answer. B. p + 5 = – 3 + (– 5) +(– 5) p = – 8 Add – 5 to both sides to isolate the variable. Check p + 5 = – 3 ? – 8 + 5 = – 3 ? – 3 = – 3 Course 2 Substitute – 8 for p in the original equation. True. – 8 is the solution to p + 5 = – 3.

3 -6 Solving Equations Containing Integers Additional Example 1 C: Solving Addition and Subtraction Equations Solve. Check the answer. C. y – 9 = – 40 +9 +9 Check y = – 31 y – 9 = – 40 ? – 31 – 9 = – 40 ? – 40 = – 40 Course 2 Add 9 to both sides to isolate the variable. Substitute – 31 for y in the original equation. True. – 31 is the solution to y – 9 = – 40.

Equations Containing 3 -6 Solving Insert Lesson Title Here Integers Try This: Example 1 A Solve. Check each answer. A. – 3 + x = – 9 +3 +3 x = – 6 Check – 3 + x = – 9 ? – 3 + (– 6) = – 9 ? – 9 = – 9 Course 2 Add 3 to both sides to isolate the variable. Substitute – 6 for x in the original equation. True. – 6 is the solution to – 3 + x = – 9.

Equations Containing 3 -6 Solving Insert Lesson Title Here Integers Try This: Example 1 B Solve. Check the answer. B. q + 2 = – 6 +(– 2) Check q = – 8 q + 2 = – 6 ? – 8 + 2 = – 6 ? – 6 = – 6 Course 2 Add – 2 to both sides to isolate the variable. Substitute – 8 for q in the original equation. True. – 8 is the solution to q + 2 = – 6.

Equations Containing 3 -6 Solving Insert Lesson Title Here Integers Try This: Example 1 C Solve. Check the answer. C. y – 7 = – 34 +7 Check +7 y = – 27 y – 7 = – 34 ? – 27 – 7 = – 34 ? – 34 = – 34 Course 2 Add 7 to both sides to isolate the variable. Substitute – 27 for y in the original equation. True. – 27 is the solution to y – 7 = – 34.

3 -6 Solving Equations Containing Integers Additional Example 2 A: Multiplication and Division Equations Solve. Check each answer. A. b =6 – 5 b (– 5) – 5 = (– 5)6 b = – 30 Course 2 Multiply both sides by – 5 to isolate the variable.

3 -6 Solving Equations Containing Integers Additional Example 2 A Continued Check b =6 – 5 ? – 30 = 6 – 5 6 = 6 Course 2 Substitute – 30 for b in the original equation. True. – 30 is the solution to b = 6. – 5

3 -6 Solving Equations Containing Integers Additional Example 2 B: Solving Multiplication and Division Equations Solve. Check each answer. B. – 400 = 8 y 8 8 – 50 = y Course 2 Divide both sides by 8 to isolate the variable.

3 -6 Solving Equations Containing Integers Additional Example 2 B: Solving Multiplication and Division Equations Check. – 400 = 8 y Substitute – 50 for y in the original equation. ? – 400 = 8(– 50) – 400 = – 400 Course 2 True. – 50 is the solution to – 400 = 8 y.

Equations Containing 3 -6 Solving Insert Lesson Title Here Integers Try This: Example 2 A Solve. Check each answer. A. c = – 24 4 4 c 4 = 4(– 24) Multiply both sides by 4 to isolate the variable. c = – 96 Course 2

Equations Containing 3 -6 Solving Insert Lesson Title Here Integers Try This: Example 2 A Continued Check c = – 24 4 Course 2 ? – 96 = – 24 4 Substitute – 96 for c in the original equation. – 24 = – 24 True. – 96 is the solution to c = – 24. 4

Equations Containing 3 -6 Solving Insert Lesson Title Here Integers Try This: Example 2 B Solve. Check each answer. B. – 200 = 4 x 4 4 – 50 = x Course 2 Divide both sides by 4 to isolate the variable.

Equations Containing 3 -6 Solving Insert Lesson Title Here Integers Try This: Example 2 B Continued Check. – 200 = 4 x Substitute – 50 for x in the original equation. ? – 200 = 4(– 50) – 200 = – 200 Course 2 True. – 50 is the solution to – 200 = 4 x.

3 -6 Solving Equations Containing Integers Additional Example 3: Business Application In 2003, a manufacturer made a profit of $300 million. This amount was $100 million more than the profit in 2002. What was the profit in 2002? Let p represent the profit in 2002 (in millions of dollars). Profit in 2003 = p + 100 Profit in 2003 = $300 million p + 100 = 300 – 100 p = 200 The profit in 2002 was $200 million. Course 2

Equations Containing 3 -6 Solving Insert Lesson Title Here Integers Try This: Example 3 This year the class bake sale made a profit of $243. This was an increase of $125 over last year. How much did they make last year? Let x represent the money made last year. This year = x + 125 This year = $243 x + 125 = 243 – 125 x = 118 The class earned $118 last year. Course 2

Equations Containing 3 -6 Solving Insert Lesson Title Here Integers Lesson Quiz Solve. Check your answer. 1. – 8 y = – 800 2. x – 22 = – 18 3. – y 7 =7 100 4 – 49 4. w + 72 = – 21 – 93 5. Last year a phone company had a loss of $25 million. This year the loss is $14 million more last year. What is this years loss? $39 million Course 2