Express with rational denominator`((a+sqrt(-1))^3-(a-sqrt(-1))^3)/((a+sqrt(-1))^2-(a-sqrt(-1))^2)`

Explanation

`((a+sqrt(-1))^3-(a-sqrt(-1))^3)/((a+sqrt(-1))^2-(a-sqrt(-1))^2)`
`=((a+i)^3-(a-i)^3)/((a+i)^2-(a-1)^2)`
`=(2(3a^2i=i^3))/(4ai)=(2i(3a^2-1))/(4ai)=(3a^2-1)/(2a)`