INTEGRAL POWERS OF IOTA ( i )
  What is the solution of the equation x 2  + 1 = 0?   In fact we don’t have any solution to the given equation in the system of real numbers.   Why? Because x 2  + 1 = 0 gives x 2  = -1   and square of every real number is non-negative.   Then, what could we do?   We need to extend the real number system to a larger system to find the solution of the equation x 2  + 1 = 0.   In general, we have to find the solution of the equation ax 2  + bx + c = 0,   where D = b 2  – 4ac < 0.   Euler was the first mathematician to introduce the symbol i  ( Iota ) for the square root of -1, i.e. solution of the equation x 2  + 1 = 0.   Now, we have    i = √-1     i 2  = -1     i 3  = i 2  * i = -i       i 4  = ( i 2 ) 2  = ( -1 ) 2  = 1