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**[SOLVED] Dirac delta function**

## Homework Statement

Prove that [tex]\delta(cx)=\frac{1}{|c|}\delta(x)[/tex]

## Homework Equations

## The Attempt at a Solution

For any function f(x), [tex]

\int_{-\infty}^{\infty}f(x)\delta(cx) dx = \frac{1}{c}\int_{-\infty}^{\infty}f(t/c)\delta(t) dt

[/tex]

where I have used t=cx.

[tex]

=\frac{1}{c}f(0)

[/tex]

This is fine and matches RHS for c>0. But how do we get the mod sign for c<0. Why isn't the above procedure valid for c<0 as well?