slope intercept form
y = mx + b
Find the slope
slope = (y₂ - y₁)/(x₂ - x₁)
let (-2, 5) = (x₁, y₁), and (3, 9) = (x₂, y₂)
Plug in the corresponding numbers to the variables.
slope = (9 - 5)/(3 - (-2))
Simplify
slope = 4/(3 + 2)
slope = 4/5
Plug in 4/5 for m
y = mx + b
y = (4/5)x + b
Solve for b. Plug in a coordinate for x and y: I am using (3,9) in this case
x = 3, y = 9
9 = (4/5)3 + b
Simplify
9 = 12/5 + b
Isolate the b. Note the equal sign. What you do to one side, you do to the other.
9 (-12/5) = 12/5 (-12/5) + b
9 - 12/5 = b
9 - 2 2/5 = b
b = 6 3/5 or 6.6
y = 4/5x + 6.6 is your slope intercept form
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Point slope form: (y - y₁) = m(x - x₁)
(x, y) = (-2, 5), (x₁, y₁) = (3, 9)
Plug in the corresponding number to the corresponding variable
(5 - 9) = m(-2 - 3)
Simplify
-4 = m(-5)
Note the equal sign. What you do to one side, you do to the other. Isolate the m.
Divide -5 from both sides
(-4)/-5 = (-5m)/-5
-4/-5 = m
m = 4/5
you're slope = 4/5 (as seen in the equation above).
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hope this helps
