Solving Systems of Equations by Substitution and Elimination

What is the best method do you use?

y = 6x − 11

−2x − 3y = −7

• Graphing

• Substitution because a variable is defined

• Elimination because both equations are in standard form.

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

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.

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

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

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

What variable do you eliminate?

4x + 8y = 20

−4x + 2y = −30

• X because they have opposite signs

• Y because they have opposite signs

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

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

5x + y = 9

10x − 7y = −18

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

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

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

What variable do you eliminate and how?

7x + 2y = 24

8x + 2y = 30

• You pick x because it's LCM is 56

• You pick y because it's LCM is 2.

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve for x and y
3x + 2y = 16
7x + y = 19

• (-2,5)
• (-2,-5)
• (2,-5)
• (2,5)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve the system given:
3x - y = 7
2x + y = 3

• (-1,2)
• (5,4)
• (4,5)
• (2,-1)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve the system:

x+ 3y = 9

2x+ y = −2

• (3,2)

• (-2, 2)

• (3, -4)

• (-3, 4)

• (0.5, -3)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve the system:

y= 3x -13

2x +4y =4

• (5,2)

• (4, -1)

• (-4, -1)

• (5, -2)

• (-4, 1)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6