point slope form: y - y1 = m (x - x1)
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first you need to find the slope(m) by using the slope formula (seen below)
y2 - y1
m= ---------
x2 - x1
9 - 15
m= ---------
1 - (-2)
-6
m= --------- = -2
3
then choose either one of the coordinates you'd like and plug it in.
Im gonna use (-2, 15)
(y - 15) = -2 (x - (-2))
or
(y - 15) = -2 (x + 2)
slope intercept form: y = mx + b
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you can use the slope formula to find that the slope(m) is -2
y = -2x + b
you can then plug in a coordinate to find b (the y-intercept)
I'll use (-2,15)
15 = -2(-2) +b
15 = 4 + b
-4 -4
---------
11 = b
in conclusion:
the slope(m) = -2
when (-2,15) is used
x = -2
y = 15
b = 11
standard form: ax + by = c
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using the same coordinate (-2,15)
-2a + 15b = c
