Solving Equations with Elimination

Which variable would be easiest to eliminate?

• x

• y

• Neither

Answer explanation

The terms with x in them have opposite coefficients (4x and -4x), so they will be the easiest to eliminate when we add the equations together.

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve the following using elimination.

• (10,-1)

• (-1,10)

• (-1,-10)

• (-10,-1)

Answer explanation

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve using Elimination:

5x + y = 9

10x − 7y = −18

• (4, -11)

• (1, 4)

• (-1, 14)

• (-4, 29)

Answer explanation

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

7x - y = 10

-7x + y = -14

• No Solution

• (4, 1)

• Infinitely Many Solutions

• (2, -4)

Answer explanation

7x - y = 10

-7x + y = -14

All of the like terms have opposite coefficients, so both variables will be eliminated when we add the equations together. We cannot eliminate one without the other.

We are left with:

0=-4

This is a contradiction (false), so there is NO SOLUTION.

Tags

CCSS.8.EE.C.8B

Solve by elimination

-6x + 5y = 1

6x + 4y = -10

• (-1,7/5)

• (0,-1)

• (1,1)

• (-1,-1)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve by elimination:
4x+9y=28
-4x-y=-28

• (-7,0)

• (6,0)

• (-6,0)

• (7,0)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve by elimination:

7x+y=-9

-3x-y=5

• No solution

• (1,8)

• (-1,-3)

• (-1,-2)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve by elimination:
-9x - 4y = -20
5x + 4y = 4

• (-4,4)

• (4,4)

• (4,-4)

• (-4,-4)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve by elimination:

7x + y = -9

-3x - y = 5

• No solution

• (1,8)

• (-1,-3)

• (-1,-2)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

solve the system of equation using elimination

x - 2y = -19

5x + 2y = 1

• (3, -8)

• (-3, 11)

• (1, 0)

• (-3,8)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6