【简答题】已知集合A={x|x=-2n-1,n∈N * },B={x|x=-6n+3,n∈N * },设S n 是等差数列{a n }的前n项和,若{a n }的任一项a n ∈A∩B,首项a 1 是A∩B中的最大数,且-750<S 10 <-300. (Ⅰ)求数列{a n }的通项公式; (Ⅱ)若数列{b n }满足 b n =( 2 2 ) a n +13n-9 ,令T n =24(b 2 +b 4 +...
【简答题】已知数列{a n }是等差数列,数列{b n }是等比数列,且对任意的n∈N*,都有a 1 b 1 +a 2 b 2 +a 3 b 3 +···+a n b n =n·2 n+3 . (1)若{b n }的首项为4,公比为2,求数列{a n +b n }的前n项和S n ; (2)若a 1 =8. ①求数列{a n }与{b n }的通项公式; ②试探究:数列{b n }中是否存在某一项,它可以表...
【简答题】What does it take to be a well-trained nurse? The answer used to be two-year associate’s or four-year bachelor’s degree programs. But as the nursing shortage 1 , a growing number of schools and hospit...
【简答题】二 . Fill in the blanks in the following paragraph with the exact words that appear in your textbook . Fill in each blank with only ONE word. There are many different stories about the downturn in the ...
【简答题】阅读理解。 There are some very good things about open education. This way of teaching allows the students to grow as people, and to develop their own interests in many subjects. Open education allows stude...