The first one is not bad at all. Just expand out, but first sub in
Now, see it?.
Originally Posted by Dragon 1.
now, group together,
and sub in and
the method is similar with question 2. try it yourself. come back to me if you still have problems.
i got number 2 but not 3
Originally Posted by Godfather i got number 2 but not 3 since right-hand side of question 3 is more complicated, so we start our proof from right-hand side.
so, LHS=RHS, solved!