# How do you write the equation of a line in point slope form and slope intercept form that has an x-intercept of -4 and a y-intercept of -1?

May 15, 2015

When I look at this, I am confused by this drawing, and I know how to calculate this. I am going to show you something simpler.

First, point slope form is the equation
y-y1= m(x-x1)

Slope intercept form is the equation
y=mx+b

Next you have to calculate your slope.
The problem has given you two points. When you have a x and y intercept as such, you have to put it into coordinates.
This will look like
(-4,0) and (0,-1)

Remember that when given a x intercept, it is always the x intercept and then a 0. Hence, (-4,0)
When given a y intercept, it is always a 0 and then the y intercept. Hence, (0,-1)

Now that you have your two point, you must calculate the slope.
To calculate slope, the formula is:
y2-y1 / x2-x1

You have to find what the y2, y1 and x2 and x1. This is easy to find.

Here is a visual of the x1 y1 x2 y2

y2-y1 / x2-x1

-1-0 / 0-4 = -1/-4 = 1/4 (Two negatives make a positive!)
Your slope of the coordinates is 1/4

Now you can find you point slope form.
Formula = y-y1=m(x-x1)

Your point slope form= y-0= 1/4(x--4)
=y-0 = 1/4(x+4) (Two negatives make a positive!)

Now to find your slope intercept form, you first have to eliminate the brackets, then isolate the y variable.

That is all going to look like this.
To eliminate the bracket, multiply everything inside the bracket by 1/4.
To eliminate the y variable subtract 0 from y and subtract 0 from the equation.
You are then left with your slope intercept= y=mx+b