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Discussion Starter · #1 ·
Find the X and Y intercepts for 3x - 7y - 21 = 0

I can graph the points, but I have no idea how to get them.

:thanks
 

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rdf8585,

You have to get the equation into y = mx + b format to get the information you want. b is the y-intercept.

3x -7y -21 = 0
-7y -21 = 0 - 3x
-7y = -3x + 21
y = (3/7)x - 3
(3/7) is the slope of the line
3 is the y-intercept
Enter zero for x and y to see where they cross:
y = (3/7)*0 - 3
y = 0 - 3
y = -3 -> (0, -3) the y-intercept

0 = (3/7)x - 3
3 = (3/7)x
21 = 3x
7 = x -> (7, 0)

Hope this helps,
 

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Discussion Starter · #3 ·
re

Thanks. I thought it was y = mx + b, but he didn't teach it like that (which is the way I've always been taught).

I see what you did more clearly, thanks.
 
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