Stand Quietly WarmUp 13 392017 41 Solve for

Stand Quietly

Warm-Up #13 (3/9/2017) 41. Solve for x. 7 x – 9 x + 1 = -11 42. Solve for x. – (-24 + 3 x) = 9 x 43. Solve for y. 8 y + 2 = -3 y – 42

Homework (3/9/2017) 4 Worksheet: Lesson 5. 2 A Homework ALL

Warm-Up #14 (3/10/2017) 4

Homework (3/10/2017) 4 Worksheet: Lesson 5. 2 B Homework ALL

Lesson 5. 2_Solving Systems of Equations by Using Substitution

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Substitution Method: Procedure for Substitution Method 41. Solve one of the equations for one of the variables. 42. Substitute the expression found in step 1 into the other equation. 43. Now solve for the remaining variable. 44. Substitute the value from step 2 into the equation 4 5. written in step 1, and solve for the remaining variable. 46. Check your work by plugging back the ordered pair (x, y) into both equations

Substitution Method: 1. Solve the following system of equations by substitution. Step 1 is already completed. Step 2: Substitute x+3 into 2 nd equation and solve. Step 3: Substitute – 4 into 1 st equation and solve. The answer: ( -4 , -1)

1) Solve the system using substitution x+y=5 y=3+x Step 1: Solve an equation for one variable. Step 2: Substitute Step 3: Solve the equation. The second equation is already solved for y! x+y=5 x + (3 + x) = 5 2 x + 3 = 5 2 x = 2 x=1

1) Solve the system using substitution x+y=5 y=3+x Step 4: Plug back in to find the other variable. Step 5: Check your solution. x+y=5 (1) + y = 5 y=4 (1, 4) (1) + (4) = 5 (4) = 3 + (1) The solution is (1, 4). What do you think the answer would be if you graphed the two equations?

2) Solve the system using substitution 3 y + x = 7 4 x – 2 y = 0 Step 1: Solve an equation for one variable. It is easiest to solve the first equation for x. 3 y + x = 7 -3 y x = -3 y + 7 Step 2: Substitute 4 x – 2 y = 0 4(-3 y + 7) – 2 y = 0

2) Solve the system using substitution 3 y + x = 7 4 x – 2 y = 0 Step 3: Solve the equation. Step 4: Plug back in to find the other variable. -12 y + 28 – 2 y = 0 -14 y + 28 = 0 -14 y = -28 y=2 4 x – 2 y = 0 4 x – 2(2) = 0 4 x – 4 = 0 4 x = 4 x=1

2) Solve the system using substitution 3 y + x = 7 4 x – 2 y = 0 Step 5: Check your solution. (1, 2) 3(2) + (1) = 7 4(1) – 2(2) = 0