interesting

is i i real or imaginary ?

22 Answers

9
Celestine preetham ·

yes it is

39
Dr.House ·

for more information see wolfram mathworld.

39
Dr.House ·

prophet sir , i did not get your point, what do u mean by


have we got anything to support that hypothesis?

its a standard result.

341
Hari Shankar ·

that ex is irrational for rational x isnt a trivial result!

In fact while reading about this, i found that wikipedia has a stronger result that ex is irrational for any algebraic number x (Lindemann–Weierstrass theorem )

Ok thats enuf math trivia i guess :D

9
Celestine preetham ·

ln2 is transcedental

or

if
ln2=p/q

2q = ep

but ex is always irrational for x - natural nos

( frm the expansion of ex can be proved )

341
Hari Shankar ·

celestine was pretty quick to say that ln2 is irrational. have we got anything to support that hypothesis?

39
Dr.House ·

gelfund ... a russian mathematician

9
Celestine preetham ·

post it b555

39
Dr.House ·

there is even one mor einteresting example,

celestine why dont u have a try ?

9
Celestine preetham ·

nice one :)

1
platinum5 ·

celestine u have not exactly got what i meant.

ln2=q (an irrational)

this means eq=2 ( a rational).

so (irrational)irrational=2

i think it is needless to say that e is irrational.

66
kaymant ·

We have i^i = (e^{i\pi/2})^i=e^{i^2\pi/2}=e^{-\pi/2}\in \mathbb{R}

1
platinum5 ·

i am pretty sure that ln2 is irrational.

341
Hari Shankar ·

yeah, this was demonstrated by Gelfund. Your knowledge is quite deep for your age

9
Celestine preetham ·

proof by eg :

consider

y = (√2)2

if y is rational then satisfied

else if y is irrational

we have y2 = 2 which is rational

hence solution exists

9
Celestine preetham ·

the ans is yes

ive already read about that

341
Hari Shankar ·

lets open up another interesting branch.

If p and q are irrational numbers can pq be rational?

9
Celestine preetham ·

yes u r right sir

1
Riju ·

Yeh I have got i^{i}=e^{-\Pi /2} which makes it real and what anant sir has done is also right!!

66
kaymant ·

well actually ii is multi-valued. What I considered was only the principal branch. In general,
i = e^{i(2n\pi +\frac{\pi}{2})}
So, i^i = e^{i^2(2n\pi +\frac{\pi}{2})}=e^{-(2n\pi +\frac{\pi}{2})}

9
Celestine preetham ·

is

ii only equal to e-pi/2 ?

can u provide a general solution ?

1
rickde ·

it is real innit?

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