Proof of y-intercept: Prove or Disprove

[dance_sg]

Homework Statement

Prove or Disprove: In the equation y=mx+b, b is the y-intercept.

The Attempt at a Solution

I know that this statement is true, and i know that to prove anything I am suppossed to use a formula, not give examples. but how should i go about doing this if the formula is the question?

 

[rock.freak667]

At any point on the y-axis, what is the x-coordinate?

 

[Shaybay92]

The y intercept occurs when x = 0 right... that is the definition of the y intercept. Thus:

y = 0x + b... y = b
There is no real other way to prove this that isn't just being really obvious...

 

[Mentallic]

It seems to prove it to me. Even though it's obviously simple, it still does the job it's meant to.

For another "slightly" more complicated one, prove the y-intercept for the line ax+by+c=0 is always -c/b, where $b\neq 0$. This is basically the same thing, just a bit more complicated since it wouldn't usually be done in 1 simple step. Getting to quadratics complicates things more-so.