Friday, July 31, 2009

Standard form??

standard form is ax +by = c





so0o how do u write an equation in standard form for the line that contains each pair of points like:





1. (3,8), (6,4)





2. (-2, -1), (2,2)

Standard form??
find the slope (y2-y1)/(x2-x1)


(4-8)/(6-3) = -4/3


now pick a point to use (3,8)


and use point-slope y-y1 = m(x-x1)


y-8 = -4/3 (x-3)


clear the fraction by multiplying by 3


3y - 24 = -4x + 12


now get x and y on one side and everything else on the other


4x + 3y = 36


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