What is the y-value of the vertex of the function f(x)=−(x−3)(x+11)?

The zeros are x = 3 and x = −11, so the vertex lies halfway between them at x = (3 + (−11))/2 = −4. Substituting gives f(−4) = −(−4 − 3)(−4 + 11) = −(−7)(7) = 49, so the y-value is 49, choice D.

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