Steps Elimination Method

What are the steps in solving for the solution to a system of linear equations in two variables using the elimination method.

Answer explanation

5 STEPS IN SOLVING SYSTEM OF LINEAR EQUATIONS BY ELIMINATION METHOD

STEP 1:

Multiply, if necessary, one or both equations by a constant so at least one pair of like terms has the same or opposite coefficients.

STEP 2:

Add or subtract the equations to eliminate one of the variables.

STEP 3:

Solve the resulting equation.

STEP 4:

Substitute the value from Step 3 into one of the original equations and solve the other variable.

STEP 5:

Check your answer in the other equation you did not use in Step 4.

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Consider the given system. Which variable is best eliminated first?

Answer explanation

The variable x is best eliminated first because its coefficients are already additive inverses of each other.

Recall that 4x−4x=0.

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Which two equations would help you eliminate the variable y?

Answer explanation

To eliminate the variable y, both coefficients from the two equations should be additive inverses of each other.

The LCM of 4 and 9 is 36. Thus, you multiply the first equation by 9:

9(5x+4y=−30)

45x+36y=−270

Then, you multiply the second equation by 4:

4(3x−9y=−18)

12x−36y=−72

The new equations can now be added and the y variables can now be eliminated.

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Which of the following is a good start when using the elimination method to solve this system?

• multiplying the second equation by 1

• multiplying the first equation by -2

• multiplying the second equation by -1

• multiplying the first equation by 2

Answer explanation

The idea behind the elimination method is to cancel one of the variables. In order for this to be possible, the coefficients of this variable need to have the same absolute value and opposite signs.

In this example, if we multiply the second equation by −1, we would then be able to add the variable x in the first equation with −x in the second one which will result to cancellation of the said variable.

Therefore, the correct answer is multiplying the second equation by −1.

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve the following system of linear equations:

Answer explanation

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

Solve the given system of linear equations:

Answer explanation

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

What are the steps involved in solving a system of equations using the elimination method?

• Identifying the variable to eliminate, multiplying the equations by appropriate constants, and adding or subtracting the equations to eliminate the variable.

• Dividing the equations by random numbers

• Ignoring one of the equations

• Solving for the variable with no elimination

Tags

CCSS.8.EE.C.8B

CCSS.HSA.REI.C.6

In the elimination method, what operation is used to eliminate one of the variables?

• Multiplication

• Addition or subtraction

• Division

• Exponentiation

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 elimination.

−4x − 4y = 0

4x + 4y = 0

• (−6, −4)

• Infinite number of solutions

• No Solution

• (6, 4)

• (0,0)

Tags

CCSS.8.EE.C.8B