Question 171331: I've asked for help several times and have not gotten a response, is there any specific reason why my questions are being ignored.
Write an equation fo the line passing through the given points.
(3,-12) and (-4,2)
Can someone be generous enough to help me
Found 3 solutions by Edwin McCravy, Alan3354, gonzo:
Answer by Edwin McCravy(20056)   (Show Source):
Answer by Alan3354(69443)  (Show Source):
You can put this solution on YOUR website! I've asked for help several times and have not gotten a response, is there any specific reason why my questions are being ignored.
Write an equation fo the line passing through the given points.
(3,-12) and (-4,2)
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There are 2 ways to solve this (maybe more, but I know 2).
Using determinants:
|x y 1|
|-4 2 1| = 0
|3 -12 1|
x*(2-(-12) -y*(-4-3) + 48-6 = 0
14x + 7y = -42
2x + y = -6
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The slope method:
1st, find the slope, m
m = (diff in y)/(diff in x)
m = (-12 -2)/(3 - (-4))
m = -14/7 = -2
Then, use either point
y-y1 = m*(x-x1)
y-2 = -2*(x+4)
y-2 = -2x -8
y = -2x -6 (slope-intercept form)
2x + y = -6 (standard form)
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I don't know which problems are yours, but the reason I ignore problems is that they have typos, or for some reason don't make any sense. I log on, and see 400 problems to choose from. I won't waste my time on the ones that are just gibberish, or that have ambiguities.
For example, "square root of 3y+5=4"
What about it? Solve for y? Is it  , or  ?
In other cases, there's just a textbook reference, and some page numbers and problem numbers. Am I supposed to buy all the textbooks that are in use?
How about this one:
How do I solve tan@+sec@=1 ?
Answer by gonzo(654)  (Show Source):
You can put this solution on YOUR website! i was going to quit but your plea struck a chord.
your problem:
you have two points:
(3,-12)
(-4,2)
with these two points you can find the equation for the line passing through them as follows:
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the slope intercept form of the equation for a line is y = m*x + b
m is the slope
b is the y-intercept (value of y when x = 0).
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your points are coordinates where the first point of the pair is the x coordinate and the second point of the pair is the y coordinate.
general form is (x,y).
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general formula for finding the slope is:
m = (y2-y1)/(x2-x1)
let x1 = 3 and y1 = -12
let x2 = -4 and y2 = 2
formula becomes:
m = (2-(-12))/((-4)-3)
simplify:
m = 14/(-7) = -2
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your slope is -2
y = m*x + b becomes:
y = -2*x + b
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now you have to find the y intercept.
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you need to take one of those points (either one will do) and substitute in the equation.
we'll take the first 1.
the equation:
y = -2*x + b
becomes:
-12 = -2*(3) + b
-12 = -6 + b
-6 = b
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if we used the second pair of points, we should have come up with the same answer.
let's try:
we'll now take the second 1.
the equation:
y = -2*x + b
becomes:
2 = -2*(-4) + b
2 = 8 + b
-6 = b
-----
b was -6 in both cases.
we have solved for b and the equation now becomes:
y = -2*x -6
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if this equation is good, then both points should make the equation true.
let's use the first pair of points (3,-12)
y = -2*x - 6
becomes:
-12 = -2*3 -6
-12 = -6 -6
-12 = -12
first pair proves equation true
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lets use the second pair of points (-4,2)
y = -2*x - 6
becomes:
2 = -2*-4 -6
2 = 8-6
2 = 2
second pair proves equation true
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equation is:
y = -2*x-6
-----
graph of this equation is shown below:
note the y intercept is -6 which is the value of b we solved for earlier.
in the equation y = -2*x - 6, if we make x = 0, then we get y = -6.
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note the x intercept is -3.
in the equation y = -2*x - 6, if we make y = 0, then we get:
0 = -2*x - 6
which becomes:
-2*x = 6
-x = 6/2 = 3
x = -3
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everything checks out and the graph is good.
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