# Algebra 1 : How to find out if lines are parallel

## Example Questions

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### Example Question #4101 : Algebra 1

Determine if the lines are parallel and find their slopes:

Explanation:

In order to determine if two lines have the same slope first write them according to slope-intercept form, where "m" is the slope of the line:

Do that for each line:

The first line has a slope of 3, while the second has a slope of -2 meaning the lines are not parallel.

### Example Question #102 : How To Find Out If Lines Are Parallel

Find the line that is parallel to the following:

Explanation:

Two lines are parallel when they have the same slope.  We can compare slopes when we write the equation of the line in slope-intercept form

where m is the slope.  Given the original equation

we must write it in slope-intercept form to find the slope.  To do this, we will divide each term by 6.  We get

Therefore, the slope of the original line is -7.  A line that is parallel to this line needs to have a slope of -7.

Let's look at the equation of the line

We must write it in slope-intercept form.  To do this, we will divide each term by -8.  We get

The slope of this line is -7.  Therefore, it is parallel to the original line.

### Example Question #103 : How To Find Out If Lines Are Parallel

Given the equations  and , are the two lines parallel to each other?

Yes, the lines are parallel since y-intercepts are alike.

Yes, the lines are parallel since slopes are alike.

Yes, the lines are parallel since slopes are NOT alike.

No, the lines are NOT parallel since slopes are NOT alike.

No, the lines are NOT parallel since y-intercepts are NOT alike.

Yes, the lines are parallel since slopes are alike.

Explanation:

For the lines to be parallel, both the lines must have similar slopes.

Write the slope-intercept form.

The  represents the slope.  Both of the equation have a slope of negative three.  Therefore, both lines are parallel.

### Example Question #104 : How To Find Out If Lines Are Parallel

Which of the following lines is parallel to

Explanation:

If two lines are parallel, then they have the same slope.  To find the slope of a line, we write it in slope-intercept form

where m is the slope.  So given the equation

we must solve for y.  To do that, we will divide each term by 6.  We get

We can see the slope of this line is -7.  Therefore, this line is parallel to the line

because it also has a slope of -7.

### Example Question #152 : Parallel Lines

How can you tell if two lines are parallel?

Explanation:

When looking at parallel lines, the slopes on both lines must be the same.  The y-intercept (or any other characteristic) of the lines do not matter.

As long as the slopes are the same, the lines are parallel.

### Example Question #101 : How To Find Out If Lines Are Parallel

Which of the following lines are parallel to ?

Explanation:

In order to determine whether if the lines are parallel, the lines must never intersect and share a similar slope to the equation given in the problem.

The equation is already in the form of:

The variable  denotes the slope of the function.

The slope of the other line must be three to be parallel.

### Example Question #106 : How To Find Out If Lines Are Parallel

Determine if the two lines are parallel

Lines are NOT parallel

Cannot be determined

Lines are parallel

Lines are dependent

Lines are NOT parallel

Explanation:

When given the equations of a line in slope-intercept form

the lines are parallel if both of the following conditions are met

•  is the same value for both equations
•  are different values in the two equations

For the lines

we see that the  values are not the same and as such

the lines are NOT parallel.

### Example Question #107 : How To Find Out If Lines Are Parallel

Which of the following equations of a line is parallel to that of:

Explanation:

It is important to know that parallel lines have the same slope.

To see which line is parallel to the given equation you need to get all the lines in the form of , which means you need to get  by itself by bringing  to the other side.

### Example Question #108 : How To Find Out If Lines Are Parallel

Which of the following lines (expressed in slope-intercept form) is parallel to the line with the equation ?