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Question 185786: I need help writing an equation for a line given the y intercept of -4 and a point on -2 and 5.
Answer by nerdybill(7384)   (Show Source):
You can put this solution on YOUR website! I need help writing an equation for a line given the y intercept of -4 and a point on -2 and 5.
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I'll assume the point you want to cross is at (x,y) = (-2,5)
The other point is at the y-intercept at (0,-4)
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Calculating the slope (m):
m = (y2-y1)/(x2-x1)
m = (5-(-4))/(-2-0)
m = (5+4)/(-2-0)
m = 9/-2
m = -9/2
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Now, we plug in one point, say (-2,5), and the slope of -9/2 into the "point-slope" form of a line:
y-y1 = m(x-x1)
y-5 = (-9/2)(x-(-2))
y-5 = (-9/2)(x+2)
y-5 = (-9/2)x + (-9/2)2
y-5 = (-9/2)x + (-9)
y-5 = (-9/2)x - 9
y = (-9/2)x - 4 (this is what they're looking for)
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