Pre-Algebra : Graphing Lines
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Example Question #21 : Graphing Lines
What is the slope of the line formed by the following equation?
To find the slope of the line, we must write the equation in slope-intercept form or
where m is the slope and b is the y-intercept.
We must get y by itself. So, we will divide all terms by 4.
Now that it is in slope-intercept form, we can find the slope. The slope m is the coefficient of the term with the variable x. Therefore, the slope of the line
is -2.
Example Question #55 : Graphing
Find the line that is parallel to the following line:
To find a line that is parallel, we must find a line with the same slope as
When looking at an equation of a line in y-intercept form
we know m is the slope. So, to determine the slope, we must write the equations in slope-intercept form. Let's look at the equation
and write it in slope intercept form. We must divide each term by 9.
Therefore, the slope of this line is -3. Because it has the same slope as the original equation, this line is parallel to the original line.
Example Question #22 : Graphing Lines
Find the y-intercept in the following equation:
To find the y-intercept, we must first write the equation in y-intercept form
where b is the y-intercept. So,
we must solve for y. We must divide each term by 3. We get
Therefore, the y-intercept is -9.
Example Question #53 : Graphing
What is the slope of the line that contains the points 
To find the slope of a line with two points we must properly plug the points into the slope equation:
We must then assign the variables 
In this case we will plug in 
Plugging the points into the equation yields 
Perform the math to arrive at 
The answer is
Example Question #51 : Graphing
Find the y-intercept of the following equation of a line:
To find the y-intercept of an equation, we must first write it in slope-intercept form
where m is the slope and b is the y-intercept. So, in our equation of a line, we must solve for y.
We must divide each term by 3.
where -4 is the slope and 12 is the y-intercept.
Therefore, the y-intercept is 12.
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