Common Core: 8th Grade Math : Solve Systems of Two Linear Equations: CCSS.Math.Content.8.EE.C.8b

Study concepts, example questions & explanations for Common Core: 8th Grade Math

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Example Question #21 :Solve Systems Of Two Linear Equations: Ccss.Math.Content.8.Ee.C.8b

Use algebra to solve the following system of linear equations:

Possible Answers:

Correct answer:

解释:

There are a couple of ways to solve a system of linear equations: graphically and algebraically. In this lesson, we will review the two ways to solve a system of linear equations algebraically: substitution and elimination.

Substitution can be used by solving one of the equations for eitheror, and then substituting that expression in for the respective variable in the second equation. You could also solve both equations so that they are in theform, and then set both equations equal to each other.

Elimination is best used when one of the variables has the same coefficient in both equations, because you can then use addition or subtraction to cancel one of the variables out, and solve for the other variable.

For this problem, substitution makes the most sense because the first equation is already solved for a variable. We can substitute the expression that is equal to, into theof our second equation:

Next, we need to distribute and combine like terms:

We are solving for the value of, which means we need to isolate theequati的一边on. We can subtractfrom both sides:

Then divide both sides byto solve for

Remember, when we are solving a system of linear equations, we are looking for the point of intersection; thus, our answer should have bothandvalues.

Now that we have the value of, we can plug that value into thevariable in one of our given equations and solve for

Our point of intersection, and the solution to the two system of linear equations is

Example Question #22 :Solve Systems Of Two Linear Equations: Ccss.Math.Content.8.Ee.C.8b

Use algebra to solve the following system of linear equations:

Possible Answers:

Correct answer:

解释:

There are a couple of ways to solve a system of linear equations: graphically and algebraically. In this lesson, we will review the two ways to solve a system of linear equations algebraically: substitution and elimination.

Substitution can be used by solving one of the equations for eitheror, and then substituting that expression in for the respective variable in the second equation. You could also solve both equations so that they are in theform, and then set both equations equal to each other.

Elimination is best used when one of the variables has the same coefficient in both equations, because you can then use addition or subtraction to cancel one of the variables out, and solve for the other variable.

For this problem, substitution makes the most sense because the first equation is already solved for a variable. We can substitute the expression that is equal to, into theof our second equation:

Next, we need to distribute and combine like terms:

We are solving for the value of, which means we need to isolate theequati的一边on. We can subtractfrom both sides:

Then divide both sides byto solve for

Remember, when we are solving a system of linear equations, we are looking for the point of intersection; thus, our answer should have bothandvalues.

Now that we have the value of, we can plug that value into thevariable in one of our given equations and solve for

Our point of intersection, and the solution to the two system of linear equations is

Example Question #23 :Solve Systems Of Two Linear Equations: Ccss.Math.Content.8.Ee.C.8b

Use algebra to solve the following system of linear equations:

Possible Answers:

Correct answer:

解释:

There are a couple of ways to solve a system of linear equations: graphically and algebraically. In this lesson, we will review the two ways to solve a system of linear equations algebraically: substitution and elimination.

Substitution can be used by solving one of the equations for eitheror, and then substituting that expression in for the respective variable in the second equation. You could also solve both equations so that they are in theform, and then set both equations equal to each other.

Elimination is best used when one of the variables has the same coefficient in both equations, because you can then use addition or subtraction to cancel one of the variables out, and solve for the other variable.

For this problem, substitution makes the most sense because the first equation is already solved for a variable. We can substitute the expression that is equal to, into theof our second equation:

Next, we need to distribute and combine like terms:

We are solving for the value of, which means we need to isolate theequati的一边on. We can subtractfrom both sides:

Then divide both sides byto solve for

Remember, when we are solving a system of linear equations, we are looking for the point of intersection; thus, our answer should have bothandvalues.

Now that we have the value of, we can plug that value into thevariable in one of our given equations and solve for

Our point of intersection, and the solution to the two system of linear equations is

Example Question #24 :Solve Systems Of Two Linear Equations: Ccss.Math.Content.8.Ee.C.8b

Which of the following expresses the solutions to the above system of equations as an ordered pair in the form?

Possible Answers:

Correct answer:

解释:

There are a couple of ways to solve a system of linear equations: graphically and algebraically. In this lesson, we will review the two ways to solve a system of linear equations algebraically: substitution and elimination.

Substitution can be used by solving one of the equations for eitheror, and then substituting that expression in for the respective variable in the second equation. You could also solve both equations so that they are in theform, and then set both equations equal to each other.

Elimination is best used when one of the variables has the same coefficient in both equations, because you can then use addition or subtraction to cancel one of the variables out, and solve for the other variable.

For this problem, elimination makes the most sense because ourvariables have the same coefficient. We can subtract our equations to cancel out the

Next, we can divide both sides byto solve for

Remember, when we are solving a system of linear equations, we are looking for the point of intersection; thus, our answer should have bothandvalues.

Now that we have the value of, we can plug that value into thevariable in one of our given equations and solve for

We want to subtractfrom both sides to isolate the

Then divide both sides byto solve for

Our point of intersection, and the solution to the two system of linear equations is

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