posted by Jon .
I have no clue please explain
similar to "rationalizing the denominator"
Multiply top and bottom by 2+i and remember that i^2 = -1
(1+i)/(2-i) x (2+i)/(2+i)
btw, the choice that fits my answer would be D, they simply split it into 2 parts.
I don't know why they would do that