a, b, c - domain and range are both (-∞, ∞), or "all real numbers."
d. domain and range are both [0, ∞).
e. domain is all real numbers; range is all non-negative numbers.
f. domain and range are both "all real numbers except 0."
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In general, the domain of the function is the range of the inverse function, and vice versa. The exception will be for e. f(x) = 4x². There, the domain and range of the inverse function must be restricted to non-negative numbers. Otherwise the inverse relation is double-valued, so not a function.
