# Finding delta in terms of epsilon-delta definition

1. Jun 24, 2014

### Bolz

1. The problem statement, all variables and given/known data

If f(x) = 3x+1 en assume δ > 0. Assume ε>0.
Give a δ > 0 with the following property :

|x-1|< δ => |f(x) - f(1)| < ε

2. Relevant equations

3. The attempt at a solution

|f(x) - f(1)| < ε
<=> |3x+1-(3*1+1)| < ε
<=> |3x-3| < ε
<=> |x-1| < ε/3

|x-1| < δ
|x-1| < ε/3

=> δ=ε/3>0

What am I doing wrong?

2. Jun 24, 2014

### pasmith

3. Jun 24, 2014

### Bolz

Oh ok. I'm learning this on my own so I assumed it had to be wrong. Self confidence is important in math too apparently..
Anyway, thanks for checking it! :)

4. Jun 24, 2014

### HallsofIvy

Staff Emeritus
Then it would have been better to ask "Is this correct" rather than "What am I doing wrong"! You are not going to do very well assuming that you cannot do the work.

5. Jun 24, 2014

### Bolz

Sorry, you're right. I'm just struggling with a lot in life and I think my lack of self confidence leaked into doing math. Sorry again.