[tex](-3)^4[/tex] means (-3) times itself 4 times
that is (-3)(-3)(-3)(-3) which simlifies to (9)(9) which simplifies to 81
if ya wanted to do the -1, then fine, here
just remember that [tex](ab)^c=(a^c)(b^c)[/tex]
so
[tex](-3)^4=[/tex]
[tex]((-1)(3))^4=[/tex]
[tex](-1)^4(3)^4=[/tex]
[tex](1)(81)=[/tex]
81