Turn on thread page Beta
 You are Here: Home >< Maths

# Am I missing something here? watch

1. How is this true? Note: L() means Laplace transform.

I get that the exponential comes from the delta function, but why did cos(t) disappear in the Laplace transform?
2. Roughly...

Edit: I'm assuming that your asterisk represents multiplication and not convolution, in which case the result would be incorrect.

(Original post by D-Day)
How is this true? Note: L() means Laplace transform.

I get that the exponential comes from the delta function, but why did cos(t) disappear in the Laplace transform?
3. More generally, delta(t-a) f(t) = delta(t-a) f(a) everywhere.

(Edit: strictly, this isn't a meaningful statement; clearly both are 0 everywhere away from a, and at t = a both are undefined. This post is colloquial for "their integrals are equal over any interval".)

Turn on thread page Beta
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: August 6, 2009
Today on TSR

### Are you living on a tight budget at uni?

From budgets to cutbacks...

### University open days

1. Loughborough University
General Open Day Undergraduate
Fri, 21 Sep '18
2. University of Cambridge
Fri, 21 Sep '18
3. Richmond, The American International University in London
Fri, 21 Sep '18
Poll
Useful resources

## Make your revision easier

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams

Can you help? Study help unanswered threads

## Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE