All Common Core: 8th Grade Math Resources
Example Questions
Example Question #291 : Grade 8
Select the equation that best represents a linear function.
In order to determine if an equation defines a linear function, we want to make sure that the equation of the line is in slope-intercept form:
If we are unable to put an equation in this form, then the equation is not linear.
Let's take a look at our answer choices:
Notice that in this equation our value is to the third power, which does not match our slope-intercept form.
Though this equation is not written in form, we can tell straight away that this does not define a linear function because the value is to the second power.
Again, though this equation is not written in form, we can tell straight away that this does not define a linear function because the value is to the second power.
For this equation, we can solve for to make sure this equation can be written is slope-intercept form. From first glance it looks to be correct because none of our variables are written to a power. In order to tell for certain, we need to isolate the y variable on the left side of the equation.
First, we can subtract from both sides:
Next, we can divide each side by
This equation is in slope-intercept form; thus, is the correct answer.
Example Question #1 : Construct And Find The Rate Of Change Of A Function Model: Ccss.Math.Content.8.F.B.4
When Megan was younger, her parents started a saving account for her and deposited . Each month since then, her parents have deposited into the savings account.
What is the rate of change for this situation?
Remember, the rate of change is a rate that describes how one quantity changes in relation to another. If we were given a table, the rate of change would be described as followed:
If we were given a graph, then the rate of change would be the slope of the line in the graph. It could be calculated by using the formula:
For this situation, we have an initial value and a rate of change.
The initial value is what Megan started with in her savings account:
The rate of change is how her savings account changes each month. Each month her parents add ; thus, her savings account changes by each month.
Example Question #292 : Grade 8
When Megan was younger, her parents started a saving account for her and deposited . Each month since then, her parents have deposited into the savings account.
What is the initial value for this situation?
The initial value is what Megan started with in her savings account:
The rate of change is how her savings account changes each month. Each month her parents add ; thus, her savings account changes by each month.
Example Question #3 : Construct And Find The Rate Of Change Of A Function Model: Ccss.Math.Content.8.F.B.4
When Megan was younger, her parents started a saving account for her and deposited . Each month since then, her parents have deposited into the savings account.
What is the function that represents this situation?
A function is represented by an equation. When making our equation, we need to know the rate of change, or the slope, and the y-intercept, which is the initial value or starting point.
Remember, the rate of change is a rate that describes how one quantity changes in relation to another. If we were given a table, the rate of change would be described as followed:
If we were given a graph, then the rate of change would be the slope of the line in the graph. It could be calculated by using the formula:
For this situation, we have an initial value and a rate of change.
The initial value is what Megan started with in her savings account:
The rate of change is how her savings account changes each month. Each month her parents add ; thus, her savings account changes by each month.
Our equation will be in slope intercept form:
We know that the slope is the rate of change, which in this case is and the y-intercept is the initial value, which in this case is We can plug in our known values to create our equation as follows:
Example Question #2 : Construct And Find The Rate Of Change Of A Function Model: Ccss.Math.Content.8.F.B.4
When Tim was born he weighed . Each month he has gained .
What is the initial value for this situation?
The initial value is the weight that Tim started at:
The rate of change is how much he gained each month. Each month he gained ; thus, his weight changes by each month.
Example Question #5 : Construct And Find The Rate Of Change Of A Function Model: Ccss.Math.Content.8.F.B.4
When Tim was born he weighed . Each month he has gained .
What is the function that represents this situation?
A function is represented by an equation. When making our equation, we need to know the rate of change, or the slope, and the y-intercept, which is the initial value or starting point.
Remember, the rate of change is a rate that describes how one quantity changes in relation to another. If we were given a table, the rate of change would be described as followed:
If we were given a graph, then the rate of change would be the slope of the line in the graph. It could be calculated by using the formula:
For this situation, we have an initial value and a rate of change.
The initial value is the weight that Tim started at:
The rate of change is how much he gained each month. Each month he gained ; thus, his weight changes by each month.
Our equation will be in slope intercept form:
We know that the slope is the rate of change, which in this case is and the y-intercept is the initial value, which in this case is We can plug in our known values to create our equation as follows:
Example Question #6 : Construct And Find The Rate Of Change Of A Function Model: Ccss.Math.Content.8.F.B.4
What is the rate of change for the provided table?
Remember, the rate of change is a rate that describes how one quantity changes in relation to another. If we were given a table, the rate of change would be described as followed:
An input/output table displays sets of ordered pairs. The input column represents the x-values and the output column represents the y-values. We can select two sets of ordered pairs from the table to solve for the rate of change, or slope:
The the rate of change for our table is
Example Question #7 : Construct And Find The Rate Of Change Of A Function Model: Ccss.Math.Content.8.F.B.4
What is the initial value for the provided table?
The initial value is the starting place, where the input, or x-value, is . This is also known as the y-intercept. In order to solve for the initial value, we first need to know the rate of change, or the slope.
An input/output table displays sets of ordered pairs. The input column represents the x-values and the output column represents the y-values. We can select two sets of ordered pairs from the table to solve for the rate of change, or slope:
The the rate of change for our table is .
Now that we have our slope, we can use our known values and solve for the y-intercept, or the initial value.
Remember, the equation of our line will be in slope-intercept form:
Plug in the slope and a set of coordinate points from the table provided in the question:
To solve for we can subtract from both sides:
represents the y-intercept, or initial value; thus, the correct answer is .
Example Question #53 : Functions
What is the function that represents the table provided?
A function is represented by an equation. When making our equation, we need to know the rate of change, or the slope, and the y-intercept, which is the initial value or starting point.
An input/output table displays sets of ordered pairs. The input column represents the x-values and the output column represents the y-values. We can select two sets of ordered pairs from the table to solve for the rate of change, or slope:
The the rate of change for our table is .
Now that we have our slope, we can use our known values and solve for the y-intercept, or the initial value.
Remember, the equation of our line will be in slope-intercept form:
Plug in the slope and a set of coordinate points from the table provided in the question:
To solve for we can subtract from both sides:
Now that we have the slope and the y-intercept, we can plug those values in for and
Example Question #9 : Construct And Find The Rate Of Change Of A Function Model: Ccss.Math.Content.8.F.B.4
What is the initial value for the provided graph?
The initial value is the starting place, where the input, or x-value, is . This is also known as the y-intercept. In order to solve for the initial value, we first need to know the rate of change, or the slope.
To find the rate of change, or slope, we can use the following formula:
In a graph, we need to find two sets of coordinate points in order to solve for the rate of change, or slope. Looking at our graph, let's pick the following points:
We can plug these points into the formula for slope, and solve for the rate of change:
The rate of change, or slope, for the provided graph is .
*Important note: Any two points selected from the graph of the line will equal a slope of . If you selected two points and did get a value of for the slope, make sure you select two points that are on the line.
Now that we have our slope, we can use a set of coordinate points from the line and solve for the y-intercept, or the initial value.
Remember, the equation of our line will be in slope-intercept form:
Plug in the slope and a set of coordinate points from the graph provided in the question:
To solve for we can subtract from both sides:
represents the y-intercept, or initial value; thus, the correct answer is .