How do you graph 2x-3y+15=0?

1 Answer
Feb 7, 2017

Use one of 3 methods.

Explanation:

There are 3 methods to plot a graph from a given equation:

  1. Plot points: Choose x-values and work out y-values
    It is good practice to choose five x-values. (2 negs, 0 and 2 pos)

  2. y-intercept /gradient method. Change the equation to y = mx+c
    Plot the y-intercept and use m = "rise"/"run" from that point.

  3. -The intercept method. Find both intercepts:
    To find the x-intercept, make y =0
    To find the y-intercept, make x =0

(This does not work if the line passes through the origin.)

2x-3y+15 =0

2x+15 = 3y

y = 2/3x+5

1. Choose x values which are divisible by 3

x: -6" "-3" "0" "3" " 6" "larr choose
y: +1" "+3" "5" "7" "9" "larr work out

Now plot the points and join with a straight line.

2. y = 2/3x+5

Plot the y-intercept at 5.
Count 2 up and 3 to the right, repeat.
Count 2 down and 3 to the left, repeat.

3. Use 2x -3y = -15

x-int: 2x - 3(0) = -15 " " rarr x = -7 1/2
y-int: 2(0) -3y =-15" "rarr y = 5

Intercepts are at : (-7 1/2, 0) and (0,5)

The three methods will all give the graph shown:

graph{y = 2/3x+5 [-25.17, 14.83, -8.88, 11.12]}