I started doing number 4 and I’m a bit confused by it. We have that and when I did the example for I got
and when I used the formula I got that
. What’s tripping me out are the middle terms of these expressions because if what we want to show holds then
but we are not told that . I’m not sure if i’m tired and this is obvious or if is a typo and it should actually be because then the equality of the middle terms is clear.