Plotting in Maple

I have tried to use the plotting function in maple 10. But should log 10 not
give 1?

http://www.tulsoba.com/pictures/plot.JPG

Another thing I have tried to declare the function:

f:= 2*x;

but how do I calculate f(2)? I have tried:

f(2);
f(x =2);

but it does not work.


.