Slope Intercept form of line through (6, -2) w/ slope m=1/3  TOPIC_SOLVED

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Slope Intercept form of line through (6, -2) w/ slope m=1/3

Postby mizkej on Thu Apr 23, 2009 3:51 am

Hi Everybody! :wave:

This is the problem I am gtrying to solve:

Write the equation ( in slope-intercept form ) of the line through (6, -2) with the slope 1/3.

I am just stuck. I see the slope and the first point but I have drawn a blank on where even to start.

Thanks in advance for your help. :roll:
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Postby stapel_eliz on Thu Apr 23, 2009 12:06 pm

mizkej wrote:Write the equation ( in slope-intercept form ) of the line through (6, -2) with the slope 1/3.

To learn, in general, how to find line equations when given a slope and a point (or just two points), try here.

Then note that you have the point (x1, y1) = (6, -2) and the slope m = 1/3. These will plug nicely into the "point-slope form": y - y1 = m(x - x1).

So plug the given values into the given formula, and solve for "y=" to convert point-slope form into slope-intercept form. :wink:

If you get stuck, please reply showing how far you have gotten. Thank you! :D
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Re: Slope Intercept

Postby mizkej on Sun Apr 26, 2009 2:30 am

:oops:
I think I've got it..

1/3 (x - 6) = y-(-2)
1/3 x - 2 = y + 2
1/3 x -2 =y -2
1/3x -2 - -2 = y
1/3 x -4 = y

y = 1/3x -4!

right? :confused:

thanks so much :wave:
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  TOPIC_SOLVED

Postby stapel_eliz on Sun Apr 26, 2009 11:59 am

mizkej wrote:1/3 (x - 6) = y-(-2)
1/3 x - 2 = y + 2
1/3 x -2 =y -2
1/3x -2 - -2 = y
1/3 x -4 = y

How did the "y + 2" become a "y - 2"? How did "- (-2)" become "-2"? :oops:

You were fine up to here:

. . . . .(1/3)x - 2 = y + 2

Now subtract "2" from either side:

. . . . .(1/3)x - 2 - 2 = y + 2 - 2

...and simplify to get the completed answer. :wink:
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Re: Slope Intercept form of line through (6, -2) w/ slope m=1/3

Postby mizkej on Sun Apr 26, 2009 11:20 pm

I took away the 2 from that side
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