有时可用函数f(x)=
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,描述学习某学科知识的掌握程度.其中x表示某学科知识的学习次数(x∈N
*),f(x)表示对该学科知识的掌握程度,正实数a与学科知识有关.
(1)证明:当x≥7时,掌握程度的增长量f(x+1)-f(x)总是下降;
(2)根据经验,学科甲、乙、丙对应的a的取值区间分别为(115,121],(121,127],(127,133].当学习某学科知识6次时,掌握程度是85%,请确定相应的学科.
考点分析:
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