Solving Systems of Equations Using Elimination by Multiplication

Solve the system by using elimination.

• (3, 5)

• (3, -5)

• (0, -4)

• (-4, -4)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve using Elimination Method:

4x + 9y = 28

-4x - y = -28

• (-7,0)

• (6,0)

• (-6,0)

• (7,0)

• (6,7)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve the system by using elimination.

• (-1, -8)

• (-8, -1)

• (-2, 6)

• (2, 6)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

What do you have to multiply the first equation by to have the x's be opposite and the same?

• 3

• 2

• -2

• -3

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve by elimination:
7x-9y=29

7x+2y=-15

• (-4,-1)

• (-1.-4)

• (-1,4)

• (-1,6)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve by elimination:
9x-4y=7

x-4y=-17

• (-1,5)

• (-7,5)

• (7,5)

• (3,5)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

________________ are two or more equations that have the same variables and work together.

• graphing lines

• elimination method

• system of equations

• table

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Put the steps for solving by ELIMINATION in order:

• Make sure the equations are lined up

• Solve for the remaining variable

• Plug that number into either original equation and solve for the other variable

• Subtract the equations to eliminate one variable

• Multiply one or both equations by a number to get common but opposite coefficients

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Consider the system 4x+3y=-1 5x+4y=1 Let's say I want to eliminate the y's. What is the least common multiple of 3 and 4?

• 12

• 4

• -3

• 3

• 5

• 1

• -1

• -12

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Consider the system

4x+3y=-1

5x+4y=1

After we do this multiplication, what will the new equations be?

​ 4(4x+3y=-1) ---> ​ (a)   x +​ (b)   y=​ (c)  

​-3(5x+4y=1)​ ---> ​ (d)   x -​ (e)   y= -3

• 16

• 12

• -4

• -15

• 3

• 5

• 1

• -1

• -12

• -3

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6