How do you graph the following equation and identify y-intercept 2y+3x= -22y+3x=2?

1 Answer
Feb 5, 2016

graph{(-3/2)x-1 [-1.32, 1.198, -1.118, 0.14]}
The y-intercept is -11

Explanation:

1) Put the equation into Slope-Intercept form (y=mx+by=mx+b).

2y+3x=-22y+3x=2
2y+cancel(3x color(red)(-3x))=-2-color(red)(3x)
2y=-2-3x
color(blue)(-1)*(2y=-2-3x)

  • Note: I multiplied the equation by color(blue)(-1 to show how you make this equation would resemble the formula. You don't have to do this step for this particular equation though because the answers are negative anyway.

-2y=2+3x

  • Note: Because of the Commutative Property of Addition you can rearrange the equation to look like the formula

-2y=3x+2
(-2y=3x+2)/-2
y=-3/2x+color(green)[(-2/2)

Now that the equation is in Slope Intercept form (y=mx+b) you know the slope (m) and the y-intercept (b).

2) Find the x-intercept

To find the x-intercept you need to set y equal to 0

  • Note: I'm going to use the original equation because it is faster but you could use the new equation too.

2color(orange)y+3x=-2
2color(orange)[(0)]+3x=-2
3x=-2
(3x=-2)/3
x=-2/3

Now, that you know the following:

  • The slope is -3/2, this means the graph will be going down or decreasing
  • The y-intercept is -1, this means the graph crosses the y-axis at the point (0,-1)
  • The x-intercept is -2/3, this means the graph crosses the x-axis at the point (-2/3, 0)

You can either:

Plot the coordinates of the x and y-intercepts and use the slope to create a line

OR

Use the Slope Intercept form equation to create points ranging between the two intercepts and then connect the dots