SAT I 一日一問:2014年11月19日
The correct answer is D
Explanation
Choice (D) is correct. Since the graph of the quadratic equation y = (negative 2 times x^2) + (b times x) + 5 assumes its maximum at x = 2, it can be written in the form y = (negative 2 ((x minus 2)^2) + k, where k is some constant. This representation is equivalent to y = (negative 2 times x^2) + (8 times x) minus 8 + k, from which it follows that b = 8 (andnegative 8 + k = 5).
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