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Ok, Well im Determining equations of Lines (Standard Form. ) And I have this question which I do not get at all. " Write the standarf form of the equation of the line passing through the points M(-4,-2) and N(4,7) Can someone please try to do this step by step, or atleast tell me what I have to do? That would reallly help me out! Thanks in Advance!

2006-10-31 10:50:34 · 3 answers · asked by kreatorgirl 2 in Science & Mathematics Mathematics

3 answers

Standard form of an equation of a line is
Ax + By = C, where A, B and C are integers and A is non-negative.
First find the slope.
Find the difference in the y-coordinates:
-2 - 7 = -9
Then find the difference in the x-coordinates:
-4 - 4 = -8
Now divide the differences
-9/-8 = 9/8
This is your slope: m = 9/8
Now use the formula:
y - y1 = m(x-x1), where m is the slope and (x1,y1) is any one of the given points.
Let's use the second point. That means x1 = 4 and y1 = 7
y - 7 = (9/8)(x-4)
We need to get rid of the fraction. Let's multiply everything by 8
8y - 56 = 9(x-4)
Distribute the 9 on the right side
8y - 56 = 9x - 36
Subtrtact 8y from each side
-56 = 9x - 8y - 36
Add 36 to each side
-20 = 9x - 8y
Answer: 9x - 8y = -20

2006-10-31 10:57:22 · answer #1 · answered by MsMath 7 · 1 0

First, find the slope of the line:
slope = m = (y2 - y1) / (x2 - x1)
m = (7 - (-2)) / (4 - (-4))
= (7 + 2) / (4 + 4) = 9/8

Now, using this slope, and any one of the two points (I'll use N), you can write the equation for the line in point-slope form:
(y - y1) = m(x - x1)

Now you can put it in standard form:
(y - 7) = (9/8)(x - 4)
y - 7 = (9/8)x - 36/8
y = (9/8)x - (9/2) + (14/2)
y = (9/8)x + 5/2
-(9/8)x + y = 5/2

2006-10-31 11:01:00 · answer #2 · answered by Anonymous · 0 1

first find the slope (7--2/4--4) = 9/8
pick one of the points (4,7)
plug into equation y-7 = (9/8)(x-4)
simplify: y-7 = 9/8x - 36/8
simplify: y = 9/8x -36/8 + 56/8
y = 9/8x + 20/8
8y = 9x +20
9x-8y+20 =0

2006-10-31 11:01:49 · answer #3 · answered by davidosterberg1 6 · 0 0

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