why (-2-i)/(-1+2*i)=i

(-2-i ) / (-1 + 2i) =

-(2 + i) / (-1 + 2i) =

(2 + i ) / -(-1 + 2i) =

(2 + i) / (1 - 2i)      multiply the top and the bottom by the conjugate of 1 - 2i...i.e., (1 + 2i)......so we have

(1 + 2i)(2 + i) / [ 1 - 4i² ] =    (remember, i² = -1)

(2 + 4i + i + 2i²)/ (5) =

(5i) / 5  =  i