what is the domain of the function
f(x)= 1/root([x]^2-[x]-6)
since f is undefined when the denominator is zero, the domain is all reals except where
√(x^2 - x - 6) = 0
since √0 = 0, the domain is where
x^2 - x - 6 = 0, or
(x-3)(x+2) = 0
domain is thus all reals except -2 and 3