27^x^2-3x=1/3 (reads: 27 to the power of x-squared minus 3x, equals 1/3.)

so far i've gotten down to -9 plus or minus the square root of 69, over 6. I ahve done this problem and variations of the this problem three times now, and for some reason i am doing something wrong everytime with the radical...you don't have to give me the answer;I am just trying to figure out what my next step is because I am obviously messing up somewhere...