Math

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We let √-1 = i. This number is never exist in this world, we call it "an imaginary numer"(虚数). We call the numbers equal the real numbers (実数) plus the imaginary numbers the complex numbers (複素数). But, they should exist in another world where we can never imagin.

For example, have a look at this graph.

 

Where are the solutions? The imaginary axis should be somewhere, then y=f(x) and them meet somewhere we can never imagin. I think there is a ghost world.

 

π = C/d  (C:the circumference of a circle, d:a diameter)

 

e =  lim  (1+x)^1/x

      x→0

 

e^iπ + 1 = 0

 

This is the most beautiful formula in math.

This rules real world and fantastic world.