F.4 logarithmic functions1

7^x = 3^y
xlog7=ylog3
x/y = log3/log7
(1) must be correct


if xy=log(3/7)
xy=-0.367976
but x≧0 and y≧0
xy≧0
(2) must not be correct

if x-y =0
x=y
x≧0 and y≧0
(3) may be correct



so,the anwser is (2)