Which function in vertex form is equivalent to f(x) = 4 + x2 – 2x?

Rewrite the function as x² − 2x + 4. Completing the square gives x² − 2x + 1 + 3 = (x − 1)² + 3, so the equivalent vertex form is f(x) = (x − 1)² + 3. This is choice A.

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