Algebra 1 : Functions and Lines

Study concepts, example questions & explanations for Algebra 1

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Example Questions

Example Question #16 : Perpendicular Lines

Find a line perpendicular to the line with the equation:

Possible Answers:

Correct answer:

Explanation:

Lines can be written in the slope-intercept format:

In this format,  equals the line's slope and  represents where the line intercepts the y-axis.

In the given equation:

Perpendicular lines have slopes that are negative reciprocals of each other.

First, we need to find its reciprocal.

Second, we need to rewrite it with the opposite sign.

Only one of the choices has a slope of .

 

Example Question #17 : Perpendicular Lines

Find a line perpendicular to the line with the equation:

Possible Answers:

Correct answer:

Explanation:

Lines can be written in the slope-intercept format:

In this format,  equals the line's slope and  represents where the line intercepts the y-axis.

In the given equation:

Perpendicular lines have slopes that are negative reciprocals of each other.

First, we need to find its reciprocal.

Second, we need to rewrite it with the opposite sign.

Only one of the choices has a slope of .

 

Example Question #18 : Perpendicular Lines

Find a line perpendicular to the line with the equation:

Possible Answers:

Correct answer:

Explanation:

Lines can be written in the slope-intercept format:

In this format,  equals the line's slope and  represents where the line intercepts the y-axis.

In the given equation:

Perpendicular lines have slopes that are negative reciprocals of each other.

First, we need to find its reciprocal.

Second, we need to rewrite it with the opposite sign.

Only one of the choices has a slope of .

 

Example Question #19 : Perpendicular Lines

Given the two lines:   and , are the lines perpendicular to each other?

Possible Answers:

Correct answer:

Explanation:

Write the perpendicular line slope formula.  The perpendicular slope is the negative reciprocal of the original slope.

Let  be the original equation.  The slope is .  Substitute this into the equation to find the slope of any perpendicular line.

The slope of a perpendicular line must have a slope of , which is also the slope for .

The answer is:

Example Question #3541 : Algebra 1

Select the equation of the line that is perpendicular to  .

Possible Answers:

None of the other answers.

Correct answer:

Explanation:

Lines are perpendicular if their slopes are negative reciprocals of one another. For example, the negative reciprocal of . So   is perpendicular to  because their slopes are the negative reciprocals of each other. .  A positive slope can still be the negative reciprocal as you can see.

Example Question #261 : Functions And Lines

Are the lines  and  perpendicular to each other?  If so, why?

Possible Answers:

No, because the slopes are not the negative reciprocal of each other.

Yes, because the slopes are the negative reciprocal of each other.

No, because the functions are not the negative reciprocal to each other.

Yes, because the slopes are the reciprocal of each other.

No, because the slopes are not the reciprocal of each other.

Correct answer:

No, because the slopes are not the negative reciprocal of each other.

Explanation:

The equations are already in slope-intercept form:  .  In order to determine whether the slopes are perpendicular to each other, write the formula for the slope of the perpendicular line.

The perpendicular slope is the negative reciprocal of the original slope.  Take an original equation, perhaps .

The slope of the original equation is .  Substitute this in the equation.

The perpendicular line must have a slope of .  Since this does not match the slope of , the lines are NOT perpendicular to each other.

 

The answer is:  

Example Question #22 : How To Find Out If Lines Are Perpendicular

Which of the following equations is perpendicular to the given function:

Possible Answers:

Correct answer:

Explanation:

Which of the following equations is perpendicular to the given function:

To find a line perpendicular to a given linear function, simply find the opposit reciprocal of the slope of the given function.

So, we begin with 4, the opposite reciprocal will have the opposite sign and will be the flipped fraction of 4, so it will look like this:

So we need to choose the answer with the correct slope, choose the only option with slope: 

Example Question #23 : How To Find Out If Lines Are Perpendicular

Which line is perpendicular to the following line:

Possible Answers:

Correct answer:

Explanation:

To find a line that is perpendicular to another line, we must look at the slope.  Two lines that are perpendicular have slopes that are opposite reciprocals of one another.  

Opposite reciprocals mean we change the sign and switch the numerator and denominator. Here is an example:

The reciprocal of  is 

The reciprocal of  is 

So, in the given equation of a line, 

We see that the slope is .  To find a line perpendicular to this one, we need to find a line with a slope of 

In the following equation,

We must first write it in slope intercept form.  To do that, we divide each term by .

So, the slope of this line is  which makes it perpendicular to the original line.

Example Question #21 : Equations Of Lines

Choose the lines that are perpendicular.

Possible Answers:

None of these

Correct answer:

Explanation:

Perpendicular lines have slopes that are negative reciprocals of each other.

For example, the negative reciprocal of 2 is   and the negative reciprocal of   would be 5.

Thus,  

 

is perpendicular to   

.

Example Question #23 : Perpendicular Lines

Find the line that is perpendicular to the following:

Possible Answers:

Correct answer:

Explanation:

Two lines are perpendicular if their slopes are opposite reciprocals of each other (opposite:  different signs,  reciprocal:  numerator and denominator are switched).

To find the slopes, we will write the original equation in slope-intercept form

where m is the slope.  Given the original equation

we must solve for y.  To do that, we will divide each term by -9.  We get

Therefore, the slope of this line is -6.  We must find a line that has a slope that is the opposite reciprocal of this line.  The opposite reciprocal slope of -6 is .  


Let's look at the line

We must write it in slope-intercept form.  To do that, we will divide each term by 12.  We get

We can simplify to

The slope of this line is .  Therefore, it is perpendicular to the original line.

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