Simplify : `sqrt(-81)+sqrt(-64), i^2+1/i^2,i^-106`

Explanation

`sqrt(-81)+sqrt(-64)=sqrt(9^2i^2)+sqrt(8^2i^2)=9i+8i=17i`
`i^2+1/i^2=-1+1/-i=-2`
`i^-106=i^-(4xx26+2)=i^-2=1/i^2=-1`