(3 log3 5/log5 3 - 5 1/log5 3 + 7 log7 49)1/2
Log(1/2)4*log(3) 9:log(7) 1/7 = log(1/2) (1/2)^(-2)*log(3) (3^2):log(7) 7^(-1) ==(-2)*2 : (-1) = 4