Expert: Bobby Soltani - 7/31/2004

Question
    1)How can you change the equation :
y-3=(-5/6)(x-2) to  
y-3=(-5/6)x+(5/3)     ?

    2)How do you know which equation to use which slope intercept form to use?  

Answer
Hi Samson,

1)  x(y + z) = xy + xz.

Example 1: 5 (3 + 2) = 5*3 + 5*2 = 15 + 10 = 25
Example 2: 6 (x - 3) = 6*x +(6)*(-3) = 6x - 18

For our problem: (-5/6)(x - 2) = (-5/6)*x + (-5/6)*(-2) =

(-5/6)x + (10/6)

10/6 reduces to 5/3 by dividing the top and bottom by 2.

2)  There is really only one equation for a line. The form you put it in is up to you or your teacher.  the form y = mx + b is often used because it is easy to graph.  For instance, if you have y = 3x + 2, you know that the line crosses the y axis at y = 2.  Then, since the slope is 3( or 3/1) you go up 3 and to the left one and draw another point.  Then, you just connect the two points to draw the line.  For the problem above, you know that it crosses the y - axis at y = 5/3.  Then you go down 5 and to the left 6 from there and draw another point.  Then, connect them to form a line.

Let me know if didn't answer your question.  I hope this helps.

Bobby