What does " => " mean in mathematics in proofs?

The task is as follows:

Verify the truth of the statement by means of direct proof:

|z| = 1 => z^n / (1 + z^2n) ∈ IR , z ∈ C

How should the arrow be interpreted, and what does it mean for the proof? It's an equation on one side and a term on the other, but what is that supposed to tell me? What should the proof reveal, and what's the best way to proceed?

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bergquelle72
4 months ago

This follows:

In words, there is:

From |z ==1 follows z^n / (1 + z^2n) is an element of IR , where zε C

Or a little longer and more meaningful:

If we have a zε C, for which |z = = 1 applies, then z^n / (1 + z^2n) is an element of IR.

This is now a mathematical statement (short: sentence) and would be to prove.

evtldocha
4 months ago
Reply to  Jeremy Edberg

That’s exactly what has to come out…

bergquelle72
4 months ago
Reply to  Jeremy Edberg

Yeah, that’s right.

eterneladam
4 months ago

That you do not know the meaning of => if you have such tasks, I see as bad joke.

Proof:

|z| = 1

=> z z_ = 1 (I write the “quer” for complex conjugation behind the z…)

=> z_ = 1 / z

=> z^n / (1 + z^2n) = z_^(-n) / (1 + z_^(-2n)

Expand with z_^(2n):

… = z_^(n) / (z_^(2n) + 1)

This is now the same as z^n / (1 + z^2n) with a large cross-section, which means that the number z^n / (1 + z^2n) is equal to its complex conjugated, thus real.

Spyro2482
4 months ago

Greater or equal.

Kaenguruh
4 months ago
Reply to  Spyro2482

No, that would be “>=”. This sign is called “follow”.

Spyro2482
4 months ago
Reply to  Kaenguruh

Mathe has never been my strength. But program it.

Kelec
4 months ago

I also do not know any language where this operator would have the same meaning in all the languages known to me.

In C# zB there is the => operator but it is used here for lambdas and expression bodies.

Kaenguruh
4 months ago

Although efficient software development requires similar skills as they are necessary to understand mathematics.