Which of the following functions are logarithmic? (you may select more than one answer) (assume x>0)
1) y=logx
2) y=-8ln(x²)
3) y=-0.9log-16.1((x)/(4))
4) y=0.7log0.001(x)
5) y=-log9.1(13x)
6) y=log-5(50x)