皮皮学，免费搜题
登录
搜题
【简答题】
观察下列等式： 1 1×2 =1- 1 2 ； 1 2×3 = 1 2 - 1 3 ； 1 3×4 = 1 3 - 1 4 将以上三个等式两边分别相加得： 1 1×2 + 1 2×3 + 1 3×4 =1- 1 2 + 1 2 - 1 3 + 1 3 - 1 4 =1- 1 4 = 3 4 （1）猜想并写出： 1 n(n+1) =______． （2）直接写出下列各式的计算结果： ① 1 1×2 + 1 2×3 +…+ 1 2009×2010 =______； ② 1 1×2 + 1 2×3 + 1 3×4 +…+ 1 n(n+1) =______． （3）探究并计算： 1 2×4 + 1 4×6 + 1 6×8 +…+ 1 2008×2010 =______．
拍照语音搜题，微信中搜索"皮皮学"使用
参考答案：
参考解析：
知识点：
皮皮学刷刷变学霸
举一反三
【简答题】The conversation is most probably taking place between a(n)____1_____ and a(n)____2_____. Kate is from ______3____Company. Leo cannot decide between Yangtian and Kaitian _______4___________.
【单选题】Greeting is a(n) _______ _______to a conversation when meeting people after some time.
A.
good subject
B.
proper start
C.
interesting beginning
D.
not necessary
【单选题】A client is about to have arterial blood gases drawn, and the nurse explains what an Allen's test is. What comment shows that the client understands the nurse's explanation?
A.
"Blood is drawn from the ulnar artery."
B.
"I know I have to lie down while blood is drawn."
C.
"This test is done to ensure adequate collateral circulation."
D.
"Direct pressure has to be placed over the site for 15 minutes after blood is drawn."
【简答题】A．Taking off his shoes. B．Washing his hands in a pool. C．Washing his hands in a stone basin. D．Bowing to the hosts.
【简答题】某施工场地方格网及角点自然标高如题图示,方格网边长a=40m,设计要求泄水坡度沿长度方向为2‰,沿宽度方向为1‰,是确定场地设计标高(不考虑土的可松性影响),并计算挖填土方工程量。
【单选题】According to Dr. Jeol Hiderbrand what accounts for his ageless energy?
A.
His ancestors.
B.
His parents.
C.
Heredity.
D.
Hard working.
相关题目：