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Laplace transform of t

Step by step, with the reason for every step · The Laplace transform · Differential Equations

Step by step

The question

Question: find the Laplace transform of t.

ℒ{t} =

1 The idea

The Laplace transform turns a function of t into a function of s.

It is an integral, but we almost never work it out: we use a table made from it.

ℒ{f(t)} = ∫ from 0 to ∞ of e^(−st) f(t) dt

The table rows we need.

tn → n!sn + 1

2 Use the table

Each part by its row: t gives 1/s².

ℒ{t} = 1s2

3 Check

Let's check: read the table backwards.

1/s² comes from t: the question.

Right!

backwards: 1s2 → t

Let's look back.

First: the idea.

Then: use the table.

Last: check.

Answer
ℒ{t} = 1s2

Your turn

Try this one yourself, then check:

Find the Laplace transform of ℒ{1}
Show the answer
ℒ = 1s

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