Solving Two Variable System of Equations

What is the best method to use?

−4x − 2y = −12

4x + 8y = −24

• Graphing

• Substitution because a variable is defined

• Elimination because the equations are in standard form.

What is the best method to use?

y = −3x + 5

5x − 4y = −3

• Graphing

• Substitution because a variable is defined

• Elimination because the equations are in standard form

What is the best method to use?

4x + 8y = 20

−4x + 2y = −30

• Graphing

• Substitution because a variable is defined

• Elimination because the equations are in standard form

What is the proper way to set up the equation to begin solving?

y = 6x − 11

−2x − 3y = −7

• -2(-11) -3y= -7

• -2(6x-11) -3y = -7

• -2x -3(11) = -7

• -2x - 3(6x-11)= -7

What variable do you eliminate?

4x + 8y = 20

−4x + 2y = −30

• X because they have opposite signs

• Y because they have opposite signs

What is the proper set up to solve the equation?

• -7(11) -2y = -13

• -7(2y +11)-2y = -13

• -7x -2(11) =-13

• -7x - 2(2y+11)= -13

What variable do you eliminate, and what do you multiply the equation(s) by?

• You eliminate x, and multiply the top equation by -2

• You eliminate y, and multiply the top equation by 7

Solve for x and y
5x + 3y = 7
y = 4

• (4,1)

• (4,-1)

• (1,4)

• (-1,4)

Solve the system:

x+ 3y = 9

2x+ y = −2

• (3,2)

• (-2, 2)

• (3, -4)

• (-3, 4)

• (0.5, -3)

Let's solve a system by GRAPHING. Put the steps in order from first to last.

• Solve both equations for y to get slope-intercept form

• Graph both lines using the slope and y-intercept

• The intersection point is the solution