Has LaTeX changed?!?

$\displaystyle \ln^p(x)$

[ math]\ln^p(x)[/tex]

$\displaystyle (-1)^{p+1}$

[ math](-1)^{p+1}[/tex]

That is what I put and I don't understand why it doesn't work? Exponents are messed up or something

$\displaystyle x^p$

[math ]x^p[/tex]