Question 373807
www.purplemath.com is a good place to start.
All three are used to describe a straight line.
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Slope-intercept form:
http://www.purplemath.com/modules/strtlneq.htm
y = mx + b
where
m is the slope
b is the y-intercept (point at which it crosses the y-axis)
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Point-slope form:
http://www.purplemath.com/modules/strtlneq2.htm
y - y1 = m(x - x1)
is basically used when you are given one point (x1, y1) and a slope and you want to determine the equation of the line.
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Standard form is in the form: (not used too often)
Ax + By = C