Solving equations - When to take logarithms?

[dcgirl16]

How do i know when to take the ln of both sides to solve an equation for example would i for y=10^(1-x)-(1-x)^10

 

[olgranpappy]

you try it and see if it works

 

[Gib Z]

If theirs an 'e' on either side and you want to get rid of it, ie you have e^x and you only want x.