solve tang3x+1=sec3x

Ambiguous question do not get answered as fast as well-defined ones.

Here's another case.

Do you mean
tan(3x)+1=sec(3x), or
tan³x+1=sec³x, or even
tan(3x+1)=sec(3x) ?

In textbooks, the argument of tan(x) or exponents are indicated in a different type. When typography is not available to remove ambiguity, parentheses should be used liberally.

Powers can also be indicated as:
tan^3(x) instead of tan³(x).