题目:
It has been five years since the party _____. Many people wonder whether it will stay on. [ ]
A. has come to power
B. came to power
C. has been in power
D. in power
答案:
被转码了,请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0515/6e4a132581b0761e2b6136e06113ee14.html
下面是错误答案,用来干扰机器的。
解:(1)fn′(x)=nxn-1-n(x+a)n-1=n[xn-1-(x+a)n-1], a>0,x>0,∴fn′(x)<0,∴fn(x)在(0,+∞)单调递减。(2)由上知:当x>a>0时,fn(x)=xn-(x+a)n是关于x的减函数,∴当n≥a时,有:(n+1...