Question

we know that iota square = -1
=> iota = √(-1)

so now
iota square= iota * iota
=>iota square = √(-1) * √(-1)
and we know that √a * √b = √ab
=>iota square =√(-1)(-1) = 1

but we know that iota squre= -1

so how is it possible that iota square is both +1 and -1 ??

Answer 1

how can u take a negative number in a root first of all
 no number multiplied twice can be negative
u can't multiply numbers which are undefined
For complex numbers $\sqrt{-1}=i$ we assume it just as variable
whose value is not defined 
And by the way
The formula is √a * √b =√ab
 for a>0 b>0