Standard Form Linear Equation

Ax+By+C=0

"A" and "B" are both coefficients of x and y. "C" is a constant term (just a number).

application: Solve for y:
Ax+By+C=0
By=-Ax-C
y=(-Ax/B)-(C/B)

y=mx+b
Therefore we see that m=-A/B and b=-C/B

Point Slope Form

y-y1=m(x-x1)

Where m=slope & (x1,y1) corresponds to specific points on the coordinate
example: Consider the line 2x+3 and write its equation in point slope form
Graph the line: y=2x+3
Slope=2
Y-Intercept=3
x__________y
-1_________1
0__________+3
-2_________-1


y-y1=m(x-x1)
y-1=2(x-(-1)) or in simplified form y-1=2(x+1)
OR
y-3=2(x-0) or in simplified form y-3=2x
OR
y-1=2(x-(-2)) or in simplified form y+1=2(x+2)

Slope y-Intercept Form

y = mx + b
m is slope and b is y-intercept.

ex) Write the slope y-intercept form for the points (-2, 1) and (4, 4).

First find slope
= (y2 - y1)/(x2 - x1)
= (4 - 1)/(4 - (-2))
= 3/6
= 0.5 or 1/2

Now that we have a y-coordinate, the slope and an x-coordinate we can find the y-intercept.
b = y - mx
b = 4 - .5(4)
b = 4 - 2
b = 2

y = 0.5x + 2

http://www.gomath.com/exercises/SlopeEquationYintercept.php
http://www.learningwave.com/lwonline/algebra_section2/yintercept2.html
http://en.wikipedia.org/wiki/Linear_equation