Sketching Logs (1 Viewer)

[qwerty44]

When sketching logs, is there a way besides plotting points to sketch the more complex ones like:



or




showing asymptotes and intercepts?

How to do you find asymptotes and intercepts without plotting points, or is that the only way?

 

[Shadowdude]

Asymptotes and intercepts can be figured out with basic calculus or algebra.

Like intercepts... just set y = 0 or x = 0 and solve. For asymptotes, take limits.

 

[qwerty44]

Ahh ok, cause that's the way I have been doing, was just wondering if there was a different way. What about the general shape of the graph? Any ways to get an idea of it before plotting points?

 

[Timske]

Ahh ok, cause that's the way I have been doing, was just wondering if there was a different way. What about the general shape of the graph? Any ways to get an idea of it before plotting points?

http://m.wolframalpha.com/input/?i=+y+=+lnx&x=0&y=0

 

[Shadowdude]

Well I only know what ln(x) is, so I could somewhat estimate what the others look like. But I'd just plot points, or use calculus - usually.

Safest way is the best way.

 

[D94]

With the first one, if you expand, it becomes ln(x²-1), which would be something like 2 log curves, as +/- x gives the same y value.