Expert: Scott A Wilson - 1/16/2010

Question
QUESTION: Im having probles with these questions could you help?

Write an equation for each line. Use slope-intercept form if possible.
* (1, 0) (1, 2)

Find the slope and y-intercept for each line that has a slope
and y-intercept
* 3x - 4y - 8 = 0

Write each equation in standard form using only integers
* 2/3y= 1/9


ANSWER: Given (x1,y1) and (x2,y2), note that m = (y2-y1)/(x2-x1).
The equation can then be found as y - y1 = m(x-x1).
Put in (x1,y1) and (x2,y2) and multiply it out.


Equations of the form y = mx + b give the slope as m and the y intercept as b.
For this equation, add 4y to both sides and then divide both sides by 4.
After this has been done, flip it around so that you have y = mx + b.

Check this out, but I believe m would be 3/4 and b would be -2.


Multiply both sides of the equation by 9.
Note that on the left side 9*2/3 is 18/3 is 6 and on the right side 9/9 is 1.


---------- FOLLOW-UP ----------

QUESTION: Im still very confused help

Answer
Note that the fist one gives a vertical line.  It is x = 1.


On the next one, if 4y is added to both side, the equation can be canged to 3x - 8 = 4y.
Flipping this around gives 4y = 3x - 8.  Next, we need to get y by itself, so divide by 4.

This will give you y = 3x/4 - 2.
The form is y = mx + b, where m is the slop and b is the y intercept.
Here, m is the fraction left when the x is removed and b is the negatve value at the end.


On the last one, since 9 = 3*3, multiply both sides by 9.
On the left side, 2y/3 * 9 is the same as 2y * 3.
On the right side, it is just 9/9.  Note that any number over itsef is 1.