I'll clarify mostly for my sake (I hadn't thought about this before)
f(x) = 1/x takes takes numbers in the range (-1, 1) to numbers outside that range, and vice versa. The representable floats are split evenly between those two sets
One minor nitpick: f(x)=1/x maps [-1,1] to [-inf,-1]u[+1,+inf] ... that is, 1 and -1 are in both sets and mapped onto themselves. However, this detail doesn't affect the argument much.
f(x) = 1/x takes takes numbers in the range (-1, 1) to numbers outside that range, and vice versa. The representable floats are split evenly between those two sets