Finite geometric sequence with a ratio greater than 1

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I am trying to solve the recurrence relation:

$ t(n)= 3T(n/2)+Cn$ (if $n>2$)

$t(2)=C$ (otherwise)

I know that there is the Master Theorem but I am trying to use the tree method. This is what I have so far: the total work that was done in each level is: $Cn(q/2)^j$ there are $\log n$ levels and therefore the sum of the work can be represented with the following geometric series:

$Cn\sum_{j=0}^L(3/2)^j$

$L=\log_2 n-1$

It's obvious that the ratio is greater than 1. Is there a way to solve this? I can't find an answer anywhere