Im supposed to factor polynomials but I have three problems I cant figure out

( when I have ^, it means its an exponent

Thanks for any help I can get

#1 12m^2 - m - 6

Im not sure what to do with the 12

#2 x^4 - 81

Im supposed to simplify

#3 x^2 over (x^2 - x)(x-1)^-1

Thanks Again