Explanation:
Linear equation
A linear equation is an algebraic equation in which each term is either a constant or the product of a constant
and (the first power of) a single variable.
Forms for 2D linear equations
Slope�intercept form
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where m is the slope of the line and b is the y-intercept, which is the y-coordinate of the point where
the line crosses the y axis. This can be seen by letting x = 0, which immediately gives y = b.
Vertical lines, having undefined slope, cannot be represented by this form. (Our solved example in mathguru.com uses this concept)
http://en.wikipedia.org/wiki/Linear_equation#Point.E2.80.93slope_form
The slope of a line in the plane is defined as the rise over the
run, m = Δy/Δx.
In mathematics, the slope or gradient of a line describes its steepness, incline, or
grade. A higher slope value indicates a steeper incline.
The
slope is (in the simplest of terms) the measurement of a line, and is defined
as the ratio of the "rise" divided by the "run" between two
points on a line, or in other words, the ratio of the altitude change to the
horizontal distance between any two points on the line. Given two points (x_{1},y_{1})
and (x_{2},y_{2}) on a line, the slope m of the line is
http://en.wikipedia.org/wiki/Slope
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