有刺激性气味。十分易溶于水(1:700),易于液化和气化。 从其构词的字形即可知道,在常温下是气态。其最常用的用途是用作制冷剂及制取硝酸、铵盐和氮肥(尿素),合成氨是十分重要的基础化工原料,是很多化工品的母料。 小小的氨气分子十分简单,毫不起眼。想要制成它,却是困扰了人类很长时间的难题。因为N2是合成氨的...
So, scratch out the 1 in the loop and replace it with n. This is the largest value of n, so the running time is denoted as O(n).O(n), or linear-time, represents just one of a myriad of possible asymptotic running times. Others include O(log2 n), O(n log2 n), O(n2), ...
1数列{an}的通项公式为an=1n2+2n,Sn数列{an}的前n和,则S8=( )A. 920B. 910C. 2945D. 2990 2数列{an}的通项公式为an=1n2+2n,Sn数列{an}的前n和,则S8=( )A.920B.910C.2945D.2990 3数列{an}的通项公式为an=1n2+2n,Sn数列{an}的前n和,则S8=( ) A. A.920 B. B.910...
Postoperative radiotherapy versus no postoperative radiotherapy in patients with completely resected non-small-cell lung cancer and proven mediastinal N2 involvement (Lung ART): An open-label, randomised, phase 3 trial. Lancet Oncol, 2022, 23(1): 104-114. 15. Hui Z, Men Y, Hu C, et al....
数列an=1/n2的前n项和公式 急啊!高中的! 只看楼主 收藏 回复我是Lzx啦 核心会员 6 RT 我是Lzx啦 核心会员 6 n平方分之一! tyj518 知名人士 11 应该没有简单公式能表示。 我是Lzx啦 核心会员 6 第三问 kissstarer流云 人气楷模 13 pi∧2╱6 kissstarer流云 人气楷模 13 看不...
Meanwhile, pore-water had basically the same changing law as groundwater in Zone 1, and the difference was mainly in the deep pore-water samples for N2 sediments. Due to the relatively dry and hot climate conditions in the Neogene period, pore-water in the N2 layer was more affected by ...
T2aN2M0IIIa期是表明癌症进入中晚期,癌细胞扩散至局部区域,但还未到达远端,此时可通过手术、放化疗等方法治疗。国际上常通过TNM分期来表示癌症临床分期。首先,T代表肿瘤大小和范围,有T1、T2、T3、T4四个等级,数字越大,肿瘤越大;而T2又分为T2a和T2b,Ta可指肿瘤直径
因为数列{an}的通项公式为an＝1n2+2n，所以an＝1n2+2n=12(1n?1n+2)，S8=12(11?13+12?14+13?15+…+18?110)=12(1+12?19? 110)=2945．故选C．
∵an+1=an+2n,a1=1,∴an+1-an=2n,则a2-a1=2,a3-a2=4,a4-a3=6,…an-an-1=2(n-1),等式两边相加得an-a1=2+4+…+2(n-1)= 2+2(n-1) 2×(n-1)=n(n-1),即an=n(n-1)+1=n2-n+1,故答案为:n2-n+1 作业帮用户 2017-04-30 举报 ©...
1 n2+2n= 1 2( 1 n- 1 n+2)∴ Sn= 1 2(1- 1 3+ 1 2- 1 4++ 1 n-1- 1 n+1+ 1 n- 1 n+2),∴ Sn= 1 2(1+ 1 2- 1 n+1- 1 n+2)∴ lim n→∞Sn= 3 4故答案为 3 4 先对通项裂项,再进行求和,从而可求数列的极限.本题以数列为载体,考查极限...