1) log 9 (9^3) = 3*log 9 (9) = 3*1 f.6
2) log 9 (1/81) = log 9 (81^(-1) ) = -1* log 9 (9^2) = (-1)*2 log 9 (9) = -1*2*1 = -2 f.6
3) log 81 (9) = log 9^2 (9) = (1/2)*1 = 1/2 f.7
4) log 1/9 (1) = 0 f.3
5) log 1/3 (81) = log 3^(-1) (3^4) = -1 log 3 (3^4) = -1*4 *log 3 (3) = -1*4*1 = -4 f.7.6