【简答题】在等差数列 中, ,则数列 的前 项和 .
【简答题】用方框中所给词或词组的正确形式填空,每个词或词组只用一次 be different from; help... with; take the subway; think of; get to; look after; move; have a picnic; stand for; grow up 1. My mother was out, so I had to my little sister ...
【简答题】(1)设{ }是等差数列,求证:数列{ }是等差数列. (2)在等差数列 中, ,其前 项的和为 ,若 ,求 .
【简答题】在等差数列 中,若公差 ,且 成等比数列,则公比 .
【判断题】急性胰腺炎起病后升高最早的酶是血清淀粉酶。
【单选题】牛顿定律适用于低速运动的宏观物体,并且只在[ ]
【简答题】在等差数列 中, ,且 成等比数列,则其公比 .
【单选题】—How do you get to school every day? —I usually _____. [ ]