What is f of x is equal to 2 x squared plus 28 x minus 5 written in vertex form?

Factor 2 from the quadratic and linear terms: f(x) = 2(x² + 14x) − 5. Completing the square gives x² + 14x = (x + 7)² − 49, so f(x) = 2(x + 7)² − 98 − 5 = 2(x + 7)² − 103. This is choice B, f(x) = 2(x + 7)² − 103.

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