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

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

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

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

7.3 Linear CombinationsGOAL• Solve a system of linear equations by linear

combinations.KEY WORDS• linear combinations

Add the EquationsSolve the linear system4x + 3y = 16 EQUATION 12x – 3y = 8 EQUATION 2SOLUTION

① ADD the equations to get an equation in one variable.

7.3 Linear CombinationsEXAMPLE 1

Add the EquationsSolve the linear system4x + 3y = 16 EQUATION 12x – 3y = 8 EQUATION 2SOLUTION

②SUBSTITUTE 4 for x into either equation and solve for y.

7.3 Linear CombinationsEXAMPLE 1

Add the EquationsSolve the linear system4x + 3y = 16 EQUATION 12x – 3y = 8 EQUATION 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 CombinationsEXAMPLE 1

7.3 Linear CombinationsCHECK POINT

Solve the linear system by Linear Combination.

1. 3x + 2y = 7-3x + 4y = 5

2. 4x – 2y = 23x + 2y = 12

3. 5x + 2y = -4-5x + 3y = 19