log(base3)x + log(base3)(2x+51) = 4

a) thank you for helping, I am a new member and love the looks of this site.

b) i am not asking you to do this, maybe just some help I am stuck

c) its not really homework, i am studying for a test on monday and just cant understand this

1) I know the rules of logs and this is where i get stuck:

log(base3)(2x+51)(x)=4

log(base3)2x^2+51x=4

2x^2+51x=3^4 --->2x^2+51x=81

? now do i divide both sides by 2? or should I have done that before i got rid of log(base3)?

p.s. I know how to factor, but not something like 2x^2+51x-81=0

Any help would be amazing, even a little input if your not sure to get me thinking. Thanks!