Slope–intercept form

Y=Mx+B

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.

[edit] Point–slope form

Point slope Form

Y-y1=m(x-x1)

where m is the slope of the line and (x1,y1) is any point on the line. The point-slope and slope-intercept forms are easily interchangeable.

The point-slope form expresses the fact that the difference in the y coordinate between two points on a line (that is, y − y1) is proportional to the difference in the x coordinate (that is, x − x1). The proportionality constant is m (the slope of the line).

Start with point slope form

y - y1 = m(x - x1)

Distribute the slope m

y - y1 = mx - mx1

Add y1 to both sides

y = mx - mx1 + y1

y = mx + b

Example:

A line has a slope of 4 and passes the point (1,2). Write the equation of the line in slope-intercept form.

y - 2 = 4(x - 1)

y - 2 = 4x - 4

y = 4x-2

Question:

Q: Given the ordered pairs of (4, - 1) (5, - 2), develop an equation in the slope intercept format.

A: to find slope of the order pairs use y2-y1/x2-x1 the slope will come out to be m= -1

use point slope form to develop equation y=m(x+b)

(m =slope)

you will get Y=-1(X-4)-1 --->Y= -X+5

Here are some online tutoring sites I recommend for extra help.

## Sunday, February 7, 2010

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