SOLUTION: ok I suck at math and I need help with some homework. The main topic is finding the equation of a line using two points or a point and slope. I can give two examples of these quest

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Question 87742: ok I suck at math and I need help with some homework. The main topic is finding the equation of a line using two points or a point and slope. I can give two examples of these questions. one is this way:
(1,-2), m=2
and the other way is...
(-1,4)(2,-1)
please heeelp!


Found 2 solutions by sax101, jim_thompson5910:
Answer by sax101(1)   (Show Source): You can put this solution on YOUR website!
the equation to find slope is y2-y1 over x2-x1. since your points are (-1,4) and (2,-1) you plug in the numbers. So it should look like -1-4 over 2+1. you then solve it across and it equals -5/3.
y2 - y1
-------- = slope
x2 - x1

-1-4
-----
2+1
answer: -5/3

Answer by jim_thompson5910(35256)   (Show Source): You can put this solution on YOUR website!
#1

If you want to find the equation of line with a given a slope of which goes through the point (,), you can simply use the point-slope formula to find the equation:


---Point-Slope Formula---
where m is the slope, and (,) is the given point

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

Plug in , , and (these values are given)

Distribute

Multiply the negatives

Multiply and to get

Subtract from both sides


Combine like terms
------------------------------------------------------------------------------------------------------------
Answer:


So the equation of the line with a slope of which goes through the point (,) is:

which is now in form where the slope is (so this shows our equation has a slope of ) and the y-intercept is

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

Graph of through the point (,)
and we can see that the point lies on the line. Since we know the equation has a slope of and goes through the point (,), this verifies our answer.
------------------------------------------------------------------------------
#2
Solved by pluggable solver: Finding the Equation of a Line
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



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

Add to both sides to isolate y


Combine like terms and to get (note: if you need help with combining fractions, check out this solver)



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

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.




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