Common Core: 8th Grade Math : Grade 8

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

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Example Questions

Example Question #10 : Compare Properties Of Two Functions: Ccss.Math.Content.8.F.A.2

The table and the equation provided represent two different functions. Which of these two functions—either table or equation form—has the greater rate of change, and what is the rate of change? 

Screen shot 2016 03 14 at 12.03.31 pm

 

Possible Answers:

Correct answer:

Explanation:

The rate of change is also known as the slope. As we have learned we can use the following equation to solve for the slope of the table:

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 slope:

The slope for our table is 

In order to determine the slope of the equation, we need to make sure the equation is in slope-intercept form: 

In this equation, the variables  and  are defined as the following:

  

The given formula for this problem was provided in slope-intercept form; thus, the slope for the equation is 

The function with the greatest rate of change will possess the greatest slope. In this case, the greater slope is , which was displayed in the function written in equation form; thus, the following answer is correct: 

Example Question #271 : Grade 8

The table and the equation provided represent two different functions. Which of these two functions—either table or equation form—has the greater rate of change, and what is the rate of change? 

Screen shot 2016 03 14 at 8.52.05 am

Possible Answers:

Correct answer:

Explanation:

The rate of change is also known as the slope. As we have learned we can use the following equation to solve for the slope of the table:

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 slope:

The slope for our table is 

In order to determine the slope of the equation, we need to make sure the equation is in slope-intercept form: 

In this equation, the variables  and  are defined as the following:

  

The given formula for this problem was provided in slope-intercept form; thus, the slope for the equation is 

The function with the greatest rate of change will possess the greatest slope. In this case, the greater slope is , which was displayed in the function written in equation form; thus, the following answer is correct: 

Example Question #272 : Grade 8

The table and the equation provided represent two different functions. Which of these two functions—either table or equation form—has the greater rate of change, and what is the rate of change? 

Screen shot 2016 03 14 at 11.59.17 am

Possible Answers:

Correct answer:

Explanation:

The rate of change is also known as the slope. As we have learned we can use the following equation to solve for the slope of the table:

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 slope:

The slope for our table is 

In order to determine the slope of the equation, we need to make sure the equation is in slope-intercept form: 

In this equation, the variables  and  are defined as the following:

  

The given formula for this problem was provided in slope-intercept form; thus, the slope for the equation is 

The function with the greatest rate of change will possess the greatest slope. In this case, the greater slope is , which was displayed in the function written in table form; thus, the following answer is correct: 

Example Question #1 : Graphing Polynomial Functions

Which of the graphs best represents the following function?

Possible Answers:

Graph_line_

Graph_parabola_

Graph_exponential_

Graph_cube_

None of these

Correct answer:

Graph_parabola_

Explanation:

The highest exponent of the variable term is two (). This tells that this function is quadratic, meaning that it is a parabola.

The graph below will be the answer, as it shows a parabolic curve.

Graph_parabola_

Example Question #1 : Understand Linear And Nonlinear Functions: Ccss.Math.Content.8.F.A.3

What is the equation of a parabola with vertex  and -intercept ?

Possible Answers:

Correct answer:

Explanation:

From the vertex, we know that the equation of the parabola will take the form for some  .

To calculate that , we plug in the values from the other point we are given, , and solve for :

Now the equation is . This is not an answer choice, so we need to rewrite it in some way.

Expand the squared term:

Distribute the fraction through the parentheses:

Combine like terms:

Example Question #1 : Functions As Graphs

Which graph depicts a function?

Possible Answers:

Question_3_incorrect_1

Question_3_incorrect_3

Question_3_correct

Question_3_incorrect_2

Correct answer:

Question_3_correct

Explanation:

A function may only have one y-value for each x-value.

The vertical line test can be used to identify the function. If at any point on the graph, a straight vertical line intersects the curve at more than one point, the curve is not a function.

Example Question #1 : How To Graph A Function

Which equation best represents the following graph?

Graph6

Possible Answers:

None of these

Correct answer:

Explanation:

We have the following answer choices.

The first equation is a cubic function, which produces a function similar to the graph. The second equation is quadratic and thus, a parabola. The graph does not look like a prabola, so the 2nd equation will be incorrect. The third equation describes a line, but the graph is not linear; the third equation is incorrect. The fourth equation is incorrect because it is an exponential, and the graph is not an exponential. So that leaves the first equation as the best possible choice.

Example Question #1 : How To Graph A Quadratic Function

Possible Answers:

 

 

 

 

None of the above

Correct answer:

 

Explanation:

Starting with

moves the parabola by  units to the right.

Similarly moves the parabola by  units to the left.

Hence the correct answer is option .

Example Question #2 : Understand Linear And Nonlinear Functions: Ccss.Math.Content.8.F.A.3

Select the equation that best represents a linear function. 

 

Possible Answers:

Correct answer:

Explanation:

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. 

This equation is in slope-intercept form; thus,  is the correct answer. 

Example Question #3 : Understand Linear And Nonlinear Functions: Ccss.Math.Content.8.F.A.3

Select the equation that best represents a linear function. 

Possible Answers:

Correct answer:

Explanation:

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. 

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