At what points (x, y, z) in space is the function f(x,y,z)=ln xyz continuous?

Question

how to solve it...????steps....????method...?????

Answer 1

ln (xyz) requires that the argument be > 0.

 

You could rewrite it as f = ln x + ln y + ln z and then you'd have to require that x,y and z all be > 0; so the function will be defined in the 'first octant' everywhere except on an axis.