High School Math : How to find out if lines are parallel

Study concepts, example questions & explanations for High School Math

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Example Questions

Example Question #1 : How To Find Out If Lines Are Parallel

Which of these lines is parallel to ?

Possible Answers:

Correct answer:

Explanation:

Lines are parallel if they have the same slope. In standard form, is the slope.

For our given equation, the slope is . Only has the same slope.

Example Question #2 : How To Find Out If Lines Are Parallel

Which of the following lines is parallel to  ? 

Possible Answers:

Correct answer:

Explanation:

Two lines that are parallel have the same slope. The slope of is , so we want another line with a slope of . The only other line with a slope of  is

Example Question #3 : How To Find Out If Lines Are Parallel

Which of these lines is parallel to ?

Possible Answers:

Correct answer:

Explanation:

Lines are parallel if they have the same slope. In standard form, is the slope.

For our given equation, the slope is . Only has the same slope.

Example Question #4 : How To Find Out If Lines Are Parallel

Which of the following lines will be parallel to ?

Possible Answers:

Correct answer:

Explanation:

Two lines are parallel if they have the same slope. When a line is in standard form, the is the slope.

For the given line , the slope will be . Only one other line has a slope of :

Example Question #1 : How To Find Out If Lines Are Parallel

Are the following lines parallel? 

 

 

Possible Answers:

It cannot be determined from the information given

No

Yes 

Correct answer:

No

Explanation:

By definition, two lines are parallel if they have the same slope. Notice that since we are given the lines in the  format, and our slope is given by , it is clear that the slopes are not the same in this case, and thus the lines are not parallel. 

Example Question #6 : Parallel Lines

Which of the following lines is parallel to the line ?

Possible Answers:

Correct answer:

Explanation:

Parallel lines have the same slope. In slope-intercept form, , is the slope. 

Here the slope is ; thus, any line that is parallel to the line in question will also have a slope of .

Only one answer choice satisfies this requirement:

Note: the answer choice  is incorrect. If put into  form, the equation becomes .  Therefore the slope is actually , not .

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