You can put this solution on YOUR website! What you posted means (with the -1 not in the exponent)
but I suspect the equation is: (with the -1 in the exponent)
These are very different equations with very different solutions.
Please re-post your question. If you really meant the first equation use
3^x=(2^x)-1
to make it clear. If the equation is supposed to be what I suspect then use:
3^x=2^(x-1)