All Common Core: 8th Grade Math Resources
Example Questions
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:
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 either or , 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 the form, 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 the of 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 the to one side of the equation. We can subtract from both sides:
Then divide both sides by to 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 both and values.
Now that we have the value of , we can plug that value into the variable 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 #182 : Expressions & Equations
Use algebra to solve the following system of linear equations:
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 either or , 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 the form, 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 the of 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 the to one side of the equation. We can subtract from both sides:
Then divide both sides by to 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 both and values.
Now that we have the value of , we can plug that value into the variable 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:
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 either or , 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 the form, 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 the of 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 the to one side of the equation. We can subtract from both sides:
Then divide both sides by to 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 both and values.
Now that we have the value of , we can plug that value into the variable 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 #187 : Expressions & Equations
Which of the following expresses the solutions to the above system of equations as an ordered pair in the form ?
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 either or , 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 the form, 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 our variables have the same coefficient. We can subtract our equations to cancel out the
Next, we can divide both sides by to 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 both and values.
Now that we have the value of , we can plug that value into the variable in one of our given equations and solve for
We want to subtract from both sides to isolate the
Then divide both sides by to solve for
Our point of intersection, and the solution to the two system of linear equations is