Elimination Method Review

Solve by elimination.

6x - y = 2

-3x - 6y = 12

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

What is the solution to this system of equations?

4x + y = 6

x - 2y = 6

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

4x+8y=20

-4x+2y=-30

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

-6x+5y=1
6x+4y=-10

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

When solving the system of equations 2x+y=-6 and 4x + 6y = 10 by elimination, a student decided to multiply the first equation by 2. What error did the student make in the elimination process?

• The student should have multiplied the first equation by -2.

• The student does not need to multiply, they can add the two equations.

• There is no error; this is a correct step in the elimination process.

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

• Add the two equations together.

• Multiply the second equation by 2 and then add the two equations.

• Multiply the second equation by -1 and then add the two equations.

• There is no need for further operations; the variables are already aligned for elimination.

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

 4x + 8y =  20
-4x + 2y = -30

• (-7,1)

• (2,-5)

• (-2,5)

• (7,-1)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

• The student should have first multiplied the first equation by -6.

• The student should have subtracted the second equation from the first, not added.

• Adding the equations directly is a correct step; there is no error.

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

4x +  8y = 20
-4x + 2y = -30
Which variable will be eliminated?

• The  x

• The  y

• The  z

• The unknown

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

what would the top equation become when you multiply everything by -1?

• 2x - 6y = 20

• -2x - 6y = -20

• -2x + 6y = 20

• -2x + 6y = -20

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6