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jehan.the.great
06-01-2006, 08:36 PM
write the equation of the lines that passes through the given two points:
a.(8, 1) (-2, -17)

?????????????
i'm soooooo lost

pka
06-01-2006, 08:47 PM
Well the change in y is –18.
The change in x is –10.
Slope is change in y divided by change in x.

jehan.the.great
06-01-2006, 08:48 PM
??
still lost

i have no clue what to do with the equation

guntram
06-01-2006, 08:58 PM
(x-8)/(-10)=(y-1)/(-17)
So
-17x+136=-10y+10
10y-17x=-126

pka
06-01-2006, 09:00 PM
Look up slope.
Then look up point slope form.
That will tell you how to do this problem.

The point being that we will not do it for you.
(Well maybe Soroban or guntram will?)

guntram
06-01-2006, 09:11 PM
y=1.7x-12.6
slope is 1.7

guntram
06-01-2006, 09:30 PM
I have a mistake

jehan.the.great
06-02-2006, 12:47 AM
ok
thanks soooooo much!

lrivetz
06-02-2006, 05:40 AM
I have a mistake

I tried solving the problem and came out with 1.8 but lost where -13.4 came from?

I used y1 -y2 / x1 - x2
1 - (-17) = 18

8 - (-2) = 10

18/10 = 1.8

How did you get -13.4 and where?

soroban
06-02-2006, 10:47 AM
Hello, jehan.the.not.so.great!

Write the equation of the lines that passes through: (8, 1) (-2, -17)
You're expected to know something about lines . . . like some formulas?

Slope of line through (x_1,y_1) and (x_2,y_2):\;\;m\;=\;\frac{y_2\,-\,y_1}{x_2\,-\,x_1}

Equation of line through (x_1.y_1) with slope m:\;\;y\,-\,y_1\;=\;m)x\,-\,x_1)

We're given two points: \,P(8,1),\;Q(-2,-17)

The slope of line PQ is: \,m\;=\;\frac{-17\,-\,1}{-2\,-\,8}\;=\;\frac{-18}{-10}\;=\;\frac{9}{5}
'
The line through (8,1) with slope m\,=\,\frac{9}{5} is: \;y\,-\,1\;=\;\frac{9}{5}(x\,-\,8)

Simplify and we get: \: y \;= \;\frac{9}{5}x\,-\,\frac{67}{5}

. . . and don't use decimals in algebra!