# Dirac delta function

1. Jul 22, 2011

### athrun200

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

2. Relevant equations

3. The attempt at a solution

Can I write, say, $f(x) \delta(x)=f(2)\delta(x)$?
Since $\delta(x)$ =0 for x$\neq$0

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2. Jul 22, 2011

### hunt_mat

I think you can say $f(x)\delta (x-2)=f(2)\delta (x)$

3. Jul 22, 2011

### athrun200

Then if x=2, left hand side will become infinity and the right hand side 0.
Is it Ok?

4. Jul 22, 2011

### athrun200

So what's wrong with my post in #1?

5. Jul 22, 2011

### Dick

The integral of $f(x) \delta(x)$ over x is f(0). The integral of $f(2) \delta(x)$ over x is f(2). So no, they aren't the same.