Solve Systems by Elimination Steps

What would be the first step in finding the solution using elimination?

• you cannot solve this using eliminiation

• cross out the 2x and 3x, because when you add them, they equal 0

• cross out the 2y and -2y because when you add them, they equal 0

• change to slope intercept form and graph

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

4x +  8y = 20

-4x + 2y = -30

When you solve these equations using the elimination method, which variable will be eliminated?

• The  x

• The  y

• The  z

• The unknown

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

To find the second variable, substitute the x or y you solved for into one of the ____.

• original equations

• one of the manipulated equations

• the top equation, always

• the bottom equation, always

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Order the algorithm (steps) to elimination

• multiply equation(s) to have opposite coefficients, if necessary

• Solve for variable

• Align like terms vertically

• add vertically

• Determine the variable to eliminate

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

The solution is...

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve the system. Plot the solution on the graph.

2x + 9y = -7 
6x - 3y = 9 

Tags

systems

Solve the system by elimination

• (8,-3)

• (3,8)

• (16,3)

• (8,3)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

What do you do in #6?

• x

• Divide by

• y

• Solve for...

• -12

• Eliminate

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

-4x - 6y = -24

4x - 7y = - 54

Let's combine (add) these 2 equations to ELIMINATE the x variable. What would our combined equations be?

• -1y = 30

• 13y = -30

• -1y = -78

• -13y = -78

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6