【简答题】小红和小丽对问题“若方程组 a 1 x+ b 1 y= c 1 a 2 x+ b 2 y= c 2 的解是 x=3 y=-4 ,求方程组 3 a 1 x+2 b 1 y=5 c 1 3 a 2 x+2 b x y=5 c 2 的解”提出各自的想法.小红说:“这个题目好象条件不够,不能求解”;小丽说:“能不能把第二个方程组的两个方程的两边都除以5,通过整体代换的方法来解决”.参考他们的讨论,你认为这...
【单选题】根据下列文章,请回答 16~20 题。 I have a friend who is a team leader of about 25 employees who are primarily women. She' s found a trick that works for her most of the time, but not always. Those staff who appear...
A.
We shall not be moved.
B.
Money means freedom.
C.
Photos taking are pleasant.
D.
There are people who are so careless about dressing.
【简答题】I have a friend who had financial problems and needed my help occasionally. He was in his final year in University while I was in my third year. He needed some money for school fees and other academic...
【简答题】已知等差数列{a n }为递增数列,满足 a 3 2 =5 a 1 +5 a 5 -25 ,在等比数列{b n }中,b 3 =a 2 +2,b 4 =a 3 +5,b 5 =a 4 +13. (Ⅰ)求数列{b n }的通项公式b n ; (Ⅱ)若数列{b n }的前n项和为S n ,求证:数列{ S n + 5 4 }是等比数列.