1. WARM UP GRAPHING LINES Write the equation in slope- intercept form and then Graph. (Lesson 4.7) 1.3x + y = 1 2.x + y = 0 3.y = -4 3

2. WARM UP GRAPHING LINES Write the equation in slope- intercept form and then Graph. (Lesson 4.7) 1.3x + y = 1 2.x + y = 0 3.y = -4 2

3. WARM UP GRAPHING LINES Write the equation in slope- intercept form and then Graph. (Lesson 4.7) 1.3x + y = 1 2.x + y = 0 3.y = -4 1

4. GRAPHING LINES Write the equation in slope- intercept form and then Graph. (Lesson 4.7) 1.3x + y = 1 2.x + y = 0 3.y = -4 WARM UP 0

5. 7.3 Linear CombinationsGOAL Solve a system of linear equations by linear combinations. KEY WORDS linear combinations

6. Add the Equations Solve the linear system 4x + 3y = 16EQUATION 1 2x – 3y = 8EQUATION 2SOLUTION ① ADD ① ADD the equations to get an equation in one variable. 7.3 Linear Combinations EXAMPLE 1

7. Add the Equations Solve the linear system 4x + 3y = 16EQUATION 1 2x – 3y = 8EQUATION 2SOLUTION SUBSTITUTE ②SUBSTITUTE 4 for x into either equation and solve for y. 7.3 Linear Combinations EXAMPLE 1

8. Add the Equations Solve the linear system 4x + 3y = 16EQUATION 1 2x – 3y = 8EQUATION 2SOLUTION ③ CHECK by substituting 4 for x and 0 for y in each of the original equations. ANSWER> The solution is (4, 0) 7.3 Linear Combinations EXAMPLE 1

9. 7.3 Linear Combinations CHECK POINT Solve the linear system by Linear Combination. 1.3x + 2y = 7 -3x + 4y = 5 2.4x – 2y = 2 3x + 2y = 12 3.5x + 2y = -4 -5x + 3y = 19