How to find out if lines are parallel - ACT Math
Card 0 of 5
Which of the following lines is parallel to:
Which of the following lines is parallel to:
First write the equation in slope intercept form. Add 
to both sides to get 
. Now divide both sides by 
to get 
. The slope of this line is 
, so any line that also has a slope of 
would be parallel to it. The correct answer is 
.
First write the equation in slope intercept form. Add
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Which pair of linear equations represent parallel lines?
Which pair of linear equations represent parallel lines?
Parallel lines will always have equal slopes. The slope can be found quickly by observing the equation in slope-intercept form and seeing which number falls in the "
" spot in the linear equation 
,
We are looking for an answer choice in which both equations have the same value. Both lines in the correct answer have a slope of 2, therefore they are parallel.
Parallel lines will always have equal slopes. The slope can be found quickly by observing the equation in slope-intercept form and seeing which number falls in the "
We are looking for an answer choice in which both equations have the same
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Which of the following equations represents a line that is parallel to the line represented by the equation 
?
Which of the following equations represents a line that is parallel to the line represented by the equation
Lines are parallel when their slopes are the same.
First, we need to place the given equation in the slope-intercept form.
Because the given line has the slope of 
, the line parallel to it must also have the same slope.
Lines are parallel when their slopes are the same.
First, we need to place the given equation in the slope-intercept form.
Because the given line has the slope of
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Line 
passes through the points 
and 
. Line 
passes through the point 
and has a 
of 
. Are the two lines parallel? If so, what is their slope? If not, what are their slopes?
Line
Finding slope for these two lines is as easy as applying the slope formula to the points each line contains. We know that line 
contains points 
and 
, so we can apply our slope formula directly (pay attention to negative signs!)
.
Line 
contains point 
and, since the y-intercept is always on the vertical axis, 
. Thus:
The two lines have the same slope, 
, and are thus identical.
Finding slope for these two lines is as easy as applying the slope formula to the points each line contains. We know that line
Line
The two lines have the same slope,
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Line 
is described by the equation 
. Line 
passes through the points 
and 
. Are the two lines parallel? If so, what is their slope? If not, what are their slopes?
Line
We are told at the beginning of this problem that line 
is described by 
. Since 
is our slope-intecept form, we can see that 
for this line. Since parallel lines have equal slopes, we must determine if line 
has a slope of 
.
Since we know that 
passes through points 
and 
, we can apply our slope formula:
Thus, the slope of line 
is 1. As the two lines do not have equal slopes, the lines are not parallel.
We are told at the beginning of this problem that line
Since we know that
Thus, the slope of line
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