SOLUTION: write an equation of this line using slope intercept form: a.) passing through the points (-2,3)(1,3) b.) passing through the point(3,1) and parallel to the line y=1/3x-2 c.) pa

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Question 117626: write an equation of this line using slope intercept form:
a.) passing through the points (-2,3)(1,3)
b.) passing through the point(3,1) and parallel to the line y=1/3x-2
c.) passing through the point (3,1)and perpendicular to the line y=1/3x-2

Answer by jim_thompson5910(35256)   (Show Source): You can put this solution on YOUR website!
a)

First lets find the slope through the points (,) and (,)

Start with the slope formula (note: is the first point (,) and is the second point (,))

Plug in ,,, (these are the coordinates of given points)

Subtract the terms in the numerator to get . Subtract the terms in the denominator to get


Reduce

So the slope is


------------------------------------------------


Now let's use the point-slope formula to find the equation of the line:



------Point-Slope Formula------
where is the slope, and is one of the given points

So lets use the Point-Slope Formula to find the equation of the line

Plug in , , and (these values are given)


Rewrite as


Distribute

Multiply and to get . Now reduce to get

Add to both sides to isolate y

Combine like terms and to get


Remove the zero term
------------------------------------------------------------------------------------------------------------
Answer:


So the equation of the line which goes through the points (,) and (,) is:

The equation is now in form (which is slope-intercept form) where the slope is and the y-intercept is

Notice if we graph the equation and plot the points (,) and (,), we get this: (note: if you need help with graphing, check out this solver)

Graph of through the points (,) and (,)

Notice how the two points lie on the line. This graphically verifies our answer.





b)


Solved by pluggable solver: Finding the Equation of a Line Parallel or Perpendicular to a Given Line


Since any two parallel lines have the same slope we know the slope of the unknown line is (its from the slope of which is also ). Also since the unknown line goes through (3,1), we can find the equation by plugging in this info into the point-slope formula

Point-Slope Formula:

where m is the slope and (,) is the given point



Plug in , , and



Distribute



Multiply



Add to both sides to isolate y

Make into equivalent fractions with equal denominators



Combine the fractions



Reduce any fractions

So the equation of the line that is parallel to and goes through (,) is


So here are the graphs of the equations and



graph of the given equation (red) and graph of the line (green) that is parallel to the given graph and goes through (,)










c)


Solved by pluggable solver: Finding the Equation of a Line Parallel or Perpendicular to a Given Line


Remember, any two perpendicular lines are negative reciprocals of each other. So if you're given the slope of , you can find the perpendicular slope by this formula:

where is the perpendicular slope


So plug in the given slope to find the perpendicular slope



When you divide fractions, you multiply the first fraction (which is really ) by the reciprocal of the second



Multiply the fractions.


So the perpendicular slope is



So now we know the slope of the unknown line is (its the negative reciprocal of from the line ). Also since the unknown line goes through (3,1), we can find the equation by plugging in this info into the point-slope formula

Point-Slope Formula:

where m is the slope and (,) is the given point



Plug in , , and



Distribute



Multiply



Add to both sides to isolate y

Combine like terms

So the equation of the line that is perpendicular to and goes through (,) is


So here are the graphs of the equations and




graph of the given equation (red) and graph of the line (green) that is perpendicular to the given graph and goes through (,)



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