Solve System of Equations by Addition or Subtraction

What is the first step in solving a system of equations by elimination?

• Rewrite the equations so the variables are all on the same side and line up the like terms.

• Get both equations in slope-intercept form.

• Get both equations equal to zero.

• Put the x terms first.

Answer explanation

We need all of the variables on the same side so that we can eventually add the left side of both equations together and add the right side of both equations together.

If the variables aren't on the same side of the equal-sign, then we can't combine like terms.

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

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. x-y=11 2x+y=19

• (10,-1)

• (-1,10)

• (-1,-10)

• (-10,-1)

Answer explanation

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

-4x - 6y = 6
4x + 6y = -4

• no solution

• (2,0)

• (-4,0)

• (0,0)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve by elimination
-6x + 5y = 1
6x + 4y = -10

• (1,-1)

• (0,-1)

• (1,1)

• (-1,-1)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

When using elimination to solve this system, which operation should be used to eliminate the x?
4x + 3y = 24
4x - 6y = 18

• Addition

• Subtraction

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve the system of equations by adding or subtracting: 4x - 3y = 5 and 2x + 3y = 11. What are the values of x and y?

• x = 6, y = 4

• x = 10, y = -2

• x = 3, y = 2

• x = 8, y = 1

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve the system of equations by elimination using addition and subtraction: 5x + 3y = 7 and 2x - 3y = 4. What are the values of x and y?

• The values of x and y are x = 3 and y = 2.

• The values of x and y are x = 4 and y = 3.

• The values of x and y are x = 1 and y = 4.

• The values of x and y are x = 2 and y = 1.

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve the system of equations by adding or subtracting: 2x + 3y = 8 and 3x - 2y = 7. What are the values of x and y?

• x = 3, y = 1

• x = 2, y = 4

• x = 4, y = 3

• x = 5, y = 2

Tags

CCSS.8.EE.C.8C

Solve the system of equations by elimination using addition and subtraction: 4x - 2y = 10 and 2x + 2y = 8. What are the values of x and y?

• x = 5, y = 2

• x = 3, y = 1

• x = 6, y = 3

• x = 2, y = 4

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6