# Laplace Transform HelpWatch

#1
Hey, I have to perform this Laplace transform and I just wanted to check if my solution is correct:

Consider:

Then,

Now, let

Then

Or:

It then follows that:

At ---->

As -->, --->

So,

As -->, -->

So,

Is this correct? Many thanks.
Last edited by tgodkin; 8 years ago
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8 years ago
#2
(Original post by tgodkin)

As -->, --->

So,

As -->, -->

So,

Is this correct? Many thanks.
Nice LaTex!

Your final answer is correct, and working looks OK all the way up to your processing for t goes to infinity.

Can't recall much on limits, but that methodology doesn't feel right; but really needs someone with more expertise to give you a definitive answer. Your working on that part seems to lose the necessary restriction between a and s. Personally, (not an expert), I'd break up the cosh and sinh into exponentials, rearrange, and then take the limit.

Someone more qualified to respond please!

Edit: Spellinge etc.
Last edited by ghostwalker; 8 years ago
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8 years ago
#3
Yeah, use the exponential definitions for cosh and sinh, like ghostwalker says .
0
quote
8 years ago
#4
(Original post by tgodkin)
So,

As -->, -->

So,

Is this correct? Many thanks.
Just realised (being dim!), although , depending on the values of a and s of course.
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#5
Thanks guys, just brought the exponentials together, was 0 anyway .
0
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8 years ago
#6
(Original post by tgodkin)
Thanks guys, just brought the exponentials together, was 0 anyway .
The outcome wasn't in doubt, just the methodology, and it's only 0 subject to certain restrictions on a and s.
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