What are the domain and range of the function f of x is equal to x to the 4th power minus 2 x squared minus 4 ?

The function is a polynomial, so its domain is all real numbers. To find its minimum, rewrite it as f(x) = (x² − 1)² − 5. Since a square is never negative, the smallest value is −5, reached when x² = 1; therefore the range is all real numbers greater than or equal to −5. This matches choice D.

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