Do Now Solve. n + 9 = 17 2. 71 + z = 55 n = 8 3. 6x = 42 4. z = -16 y 8 x = 7 = 9 y = 72

Learn to solve two-step equations.

When you solve equations that have one operation, you use an inverse operation to isolate the variable. n + 7 = 15 – 7 –7 n = 8 You can also use inverse operations to solve equations that have more than one operation. 2x + 3 = 23 You need to use another operation to isolate x. – 3 – 3 2x = 20

A two step equation is when addition/subtraction AND multiplication/division is happening to the variable. You will need to perform two steps in order to solve the equation. GOAL: Use inverse operations to isolate the variable.

Steps for Solving Two-Step Equations Draw “the center of the scale” Get rid of any number being added or subtracted to the variable by doing the inverse operation to both sides of the equation Get rid of anything being multiplied or divided to the variable by doing the inverse operation to both sides of the equation Check your answer

Example A Solve. Check each answer. 9c + 3 = 39 9c + 3 = 39 – 3 –3 Subtract 3 from both sides. 9c = 36 9c 9 = 36 Divide both sides by 9. c = 4

Example A continued Check. 9c + 3 = 39 9(4) + 3 39 Substitute 4 for c. ? = 39 Substitute 4 for c. 36 + 3 39 ? = 39 39 ? = 4 is a solution.

Example A continued Solve. Check the answer. –34 = –4m – 6 –34 = –4m – 6 + 6 +6 Add 6 to both sides. –28 = –4m –28 –4 = –4m Divide both sides by –4. 7 = m

Example A continued Check. –4m – 6 = –34 –4(7) – 6 –34 ? = –34 Substitute 7 for m. –28 – 6 –34 ? = ? = –34 –34 7 is a solution.

1. 3x + 7 = -5 2. 7 + 4y = 19 3. 7c + 6 = 48 4. –6m – 8 = –50

1 Dec 17 3x + 7 = –5 3x + 7 = –5 -7 -7 3x = –12 3x = –12 = 3 3 x = –4 YOU TRY 1 Solve 3x + 7 = –5 3x + 7 = –5 3x + 7 = –5 -7 -7 3x = –12 3x = –12 3 3 = x = –4 ANSWER The solution is –4.

Dec 17 YOU TRY 2 Solve 7 + 4y = 19 7 + 4y = 19 7 + 4y = 19 –7 – 7 4y = 12 4y = 12 4 4 = x = 3 ANSWER The solution is 3.

YOU TRY 3 Solve. Check the answer. 7c + 6 = 48 7c + 6 = 48 – 6 –6 Subtract 6 from both sides. 7c = 42 7c 7 = 42 Divide both sides by 7. c = 6

YOU TRY 4 Solve. Check the answer. –6m – 8 = –50 –6m – 8 = –50 + 8 +8 Add 8 to both sides. –6m = –42 –6m –6 = –42 Divide both sides by –6. m = 7

Lesson Quiz for Student Response Systems 1. Solve 7q + 5 = 68. A. q = 6 B. q = 7 C. q = 8 D. q = 9

Lesson Quiz for Student Response Systems 2. Solve 17h – 10 = 75. A. h = 5 B. h = 7 C. h = 9 D. h = 10