# Im trying to determine the y and x intercepts of this line.

## Homework Statement

I am trying to determine the x- and y-intercepts of the line 3x – 5y + 15 = 0.

standard form

## The Attempt at a Solution

:[/B]

To find the x-intercept (where the line crosses the x-axis), substitute 0 in for y:
3x + 5y + 15 = 0 (substituted 0 in for y)
3x + 5(0) + 15 = 0 (multiply 5 by 0)
3x + 15 = 0 (Next ,subtract 15 from both sides)
3x = -15 (divided both sides by 3)
x = -5
x-intercept = -5.

I will use this method to solve for the y-intercept.

To find the y-intercept (where the line crosses the y-axis), substitute 0 in for x:
3x + 5y + 15 = 0 (substituted 0 in for x)
3(0) + 5y + 15 = 0 (multiply 3 by 0)
5y + 15 = 0 (Next ,subtract 15 from both sides)
5y = -15 (divided both sides by 5)
y = -3
y-intercept = -3

I'm pretty sure I did it correct but i just want to be sure I understand what I'm doing and answering it correctly. Also can you guys tell me if my way is like clear, as in you can understand it. Thx alot :)

member 587159

## Homework Statement

I am trying to determine the x- and y-intercepts of the line 3x – 5y + 15 = 0.

standard form

## The Attempt at a Solution

:[/B]

To find the x-intercept (where the line crosses the x-axis), substitute 0 in for y:
3x + 5y + 15 = 0 (substituted 0 in for y)
3x + 5(0) + 15 = 0 (multiply 5 by 0)
3x + 15 = 0 (Next ,subtract 15 from both sides)
3x = -15 (divided both sides by 3)
x = -5
x-intercept = -5.

I will use this method to solve for the y-intercept.

To find the y-intercept (where the line crosses the y-axis), substitute 0 in for x:
3x + 5y + 15 = 0 (substituted 0 in for x)
3(0) + 5y + 15 = 0 (multiply 3 by 0)
5y + 15 = 0 (Next ,subtract 15 from both sides)
5y = -15 (divided both sides by 5)
y = -3
y-intercept = -3

I'm pretty sure I did it correct but i just want to be sure I understand what I'm doing and answering it correctly. Also can you guys tell me if my way is like clear, as in you can understand it. Thx alot :)

It seems correct, but why do you substitute? Do you understand that?

Sorry what do you mean by bold?

member 587159
Sorry what do you mean by bold?

Nothing, was just a code error. Could you answer the question so I can see whether you understand why you can do this to solve the exercice?

Well my dad kinda just taught me this way, so you would try to isolate the variable y( you can start with x but im starting with y). so to isolate the variable i have to move some values to the other side of the equations. I searched online and it said i should substitute the variable y for 0. I don't know why but i did ( my dad didnt tell me to do that i did it on my own). So I did and continue the way my dad taught me and got my final result.

member 587159
Well my dad kinda just taught me this way, so you would try to isolate the variable y( you can start with x but im starting with y). so to isolate the variable i have to move some values to the other side of the equations. I searched online and it said i should substitute the variable y for 0. I don't know why but i did ( my dad didnt tell me to do that i did it on my own). So I did and continue the way my dad taught me and got my final result.

Wel you can consider it this way. The y-axe has equation: x = 0, so this are all the points with x coordinate 0. You want to know where your line intersects with the y-axis, and you know that the x-coordinate should be 0. Since you say x = 0 in the equation, you will automatically get the y value corresponding with this x-value. Is this clear? (I need to go to school now btw, so I won't reply for a couple of hours)

Wow that really helps thanks alot ill keep that in mind while i answer my next problem :)

thx you !!!