how do i graph y=-3 and 2x-3y=9

Question

i need to know how to graph those two in slope-intercept form

Answer 1

Y = -3 is on the y-axis below the x-axis. So, the graph is the line parallel to the x-axis  at y= -3. 

For the second equation you need to write it in the slope intercept form like y = mx +b, where m is the slope and b is the y-intercept. So you need to solve for y.

 

2x-3y = 9

-3y = 9 -2x

y= (2/3)x - 3, now y-intercept is -3 and slope is 2/3.  You have to find the y-intercept on the y-axis at -3, from there you move 2units up (rise) and 3 units right (run). Locate this point. Now join y-intercept and this point to get the graph of the line.

Answer 2

Dear jesmin,

    Here is another point added on to the above solution.  If you look closer at the first equation, y= -3, see what it is in

 

slope intercept form,   y=mX +b. 

 

What is the slope at y= -3?   The slope is 0.  It is like walking on a flat surface.  Therefore, -3=0X +b       -3=y.