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## #1 2006-09-01 20:32:35

Devantè
Real Member

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### Writing Linear Equations Given Two Points

Exercises on Writing Linear Equations Given Two Points

Write an equation of the line that passes through the given two points.

1. (1,2) , (21,-58)
2. (5,1) , (11,-23)
3. (1,5) , (7,8)
4. (3,8) , (37,-60)
5. (29,48) , (55,9)
6. (8,-7) , (133,668)
7. (-6,-6) , (78,183)
8. (-19,10) , (47,-210)
9. (0,5) , (45,    -220)
10. (22,-41) , (58,-23)
11. (-39,-27) , (41,357)
12. (-2,-8) , (42,-63)
13. (-10,-26) , (40,-36)
14. (-5,-24) , (19,-136)
15. (-5,4) , (35,64)
16. (3,-1) , (31,-85)
17. (37,49) , (47,24)
18. (-11,-6) , (27,-215)

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## #2 2006-09-17 11:20:24

Prakash Panneer
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### Re: Writing Linear Equations Given Two Points

This is the formula for finding the equation of line when the two points ( x1, y1) and (x2, y2) are given,

(y - y1)(x2 - x1) = (x - x1) (y2 - y1).

Using this formula, we can find an equation of a line for the given points.

Letter, number, arts and science
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## #3 2007-01-25 22:55:54

littlelittle
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### Re: Writing Linear Equations Given Two Points

Hi

Stuck again..

An equation is y = mx + b where m is the slope ie. y1-y2/x1-x2.

How do i calculate 'b' without drawing n connecting the points?

Prakash - how do i put your formula to work?  Can you do 1 prob for me please?

Thanks
S

## #4 2007-01-25 23:04:59

Toast
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### Re: Writing Linear Equations Given Two Points

Well, let's take for example, the coordinates (1,4) (-3, 5).
The coordinates are of the form (x1, y1) (x2, y2), so we can substitute them into the formula:
(y - y1)(x2 - x1) = (x - x1) (y2 - y1)
(y - 4)(-3 - 1) = (x - 1)(5 - 4)
(y - 4)(-4) = (x - 1)(1)
Using the distributive law:
-4(y - 4) = 1(x-1)
-4y + 16 = x - 1
-4y = x - 17
∴                   y = -1/4x + 17/4

(I personally don't use this method [although it would probably benefit me if I did], instead, I find the gradient (y2-y1)/(x2-x1), then substitute the coordinate points in to solve for c)

Last edited by Toast (2007-01-25 23:08:21)

## #5 2007-01-26 01:39:42

littlelittle
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### Re: Writing Linear Equations Given Two Points

Thanks Toast.

Its now clear to me.

Thanks again

## #6 2010-09-30 21:30:57

smithlanger
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### Re: Writing Linear Equations Given Two Points

sounds good to me

## #7 2010-10-01 05:32:16

bobbym

Online

### Re: Writing Linear Equations Given Two Points

Hi smith;

Welcome to the forum. There are actually easier ways to do that.

In mathematics, you don't understand things. You just get used to them.
90% of mathematicians do not understand 90% of currently published mathematics.
I am willing to wager that over 75% of the new words that appeared were nothing more than spelling errors that caught on.