题目内容
（请给出正确答案）
[主观题]
在等差数列{an}中，已知a5+a8=5，那么a2+a11的值为（）A.5B.10C.15D.2
在等差数列{an}中，已知a5+a8=5，那么a2+a11的值为（）
A.5
B.10
C.15
D.20
提问人：网友sudiwei
发布时间：2022-01-07
如搜索结果不匹配，请 
A. 5%
B. 10％
C. 15%
D. 20%
E. 25%
题目内容
（请给出正确答案）
您可能会需要：
安装简答题APP，拍照搜题省时又省心！
更多“在等差数列{an}中，已知a5+a8=5，那么a2+a11的…”相关的问题
第2题
已知向量a =(3,4),b= (0, - 2),则 cos〈a,b〉=()。A.4/5B.-4/5C.2/25D.-2/25
已知向量a =(3，4)，b= (0， - 2)，则 cos〈a，b〉=（）。
点击查看答案
A.4/5
B.-4/5
C.2/25
D.-2/25
第3题
在?ABC中 ,已知a=1,b=2, cosC=-1/4(1)求 ?ABC 的周长;(2)求 sin(A+ C ) 的值.
在?ABC中 ，已知a=1,b=2, cosC=-1/4
点击查看答案
（1）求 ?ABC 的周长；
（2）求 sin(A+ C ) 的值．
第5题
某同学每次投篮投中的概率为2/3该同学投篮2次,只投中1次的概率为()。A.6/25B.9/25C.12/25D.3/5
某同学每次投篮投中的概率为2/3该同学投篮2次，只投中1次的概率为()。
点击查看答案
A.6/25
B.9/25
C.12/25
D.3/5
第7题
若a,b,C为实数,且a≠o.设甲:b2-4ac≥0,乙:ax2+bx+C-0有实数根, 则 ( )A.甲既不是乙的充分条
若a，b，C为实数，且a≠o．设甲：b2-4ac≥0，乙：ax2+bx+C-0有实数根， 则 （ ）
点击查看答案
A.甲既不是乙的充分条件，也不是乙的必要条件
B.甲是乙的必要条件，但不是乙的充分条件
C.甲是乙的充分必要条件
D.甲是乙的充分条件，但不是乙的必要条件
第8题
一个圆上有5个不同的点,以这5个点中任意3个为顶点的三角形总共有()个。A.60B.15C.5D.10
一个圆上有5个不同的点，以这5个点中任意3个为顶点的三角形总共有（）个。
点击查看答案
A.60
B.15
C.5
D.10
第9题
Generations of Americans have been brought up to believe that a good breakfast is one life’s essentials. Eating
点击查看答案
breakfast at the start of the day, we have all been told, and told again, is as necessary as putting gasoline in the
family car before starting a trip.
But for many people the thought of food first thing in the morning is by no means a pleasure. So despite all the
efforts, they still take no breakfast. Between 1977 and 1983, the latest year for which figures are available, the
number of people who didn’t have breakfast, increased by 33 percent.
For those who feel pain of guilt about not eating breakfast, however, there is some good news. Several studies
in the last few years indicate that, for adults especially, there may be nothing wrong with omitting breakfast.
“Going without breakfast does not affect performance,” said Arrold E. Bender, former professor of the nutrition
at Queen Elizabeth College in London, “nor does giving people breakfast improve performance.”
Scientific evidence linking breakfast to better health or better performance is surprisingly inadequate, and most
of the recent work involves children, not adults, “The literature”, says one researcher, Dr. Erresto at the University
of Texas, “is poor”.
The latest year for which figures could be obtained is _______.
A. the year the author wrote the article
B. 1977
C. any year between 1997 and 1983
D. 1983
