Solving Systems of Equations by Elimination with Same Coefficients

Put the steps for solving by ELIMINATION in order:

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

• Solve for the remaining variable

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

• Make sure the equations are lined up

• Subtract the equations to eliminate one variable

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

In this system x+3y=9 it'll be easiest to start by solving the first equation for x. The result of doing so is x=​9-3y. Fill in the blanks to plug that expression in and solve for y: 4(​9-3y)-2​y =-6 36-​12y-2y=​-6 36-​14y =-6 -14y=​ (a)   y=​ (b)  

• -42

• 3

• 30

• -3

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?

LCM = ​ (a)  

Multiply each equation by a number so that the coefficient of y will be 12, with one positive and one negative.

​ (b)   (4x+3y=-1)

​ (c)   (5x+4y=1)

• 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

Q2. What are the coordinates of the point?

• (2,-8)

• (-8,2)

• (0,6)

• (6,0)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

a method to solving a system of equations by getting rid of one of the variables first to solve for the other variable. 

• Systems by Graphing

• Systems by Substitution

• Systems by Elimination

• Systems by Drawing

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

• A

• B

• C

• D

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

• (-1, -5)
• (5, -1)
• (1, -5)
• (1, 5)

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

• A

• B

• C

• D

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve the system by using elimination.

• (0, 2)

• (0, 0)

• No solution

• Infinite Solutions

Tags

CCSS.8.EE.C.8B