Solve the following recurrence relations by the recursion$-$tree method:

$$a$)$ T$($n$)=4$ T$($n$/2)+$ n

$($b$)$ T$($n$)=3$T$($n$/2)+$ n$2$

$($c$)$ T$($n$)=$ T$($n$/2)+$ T$($n$/3)+$ n

$($d$)$ T$($n $)=$ T$($n$/4)+$ T$3$n$/4)+2$