给出下列算式：
32-12=8=8×1，52-32=16=8×2
72-52=24=8×3 92-72=32=8×4
…
观察上面算式，那么第n个算式可表示为______．
左边是从3开始的奇数列的平方减去从1开始的奇数列的平方，右边是8的倍数，
∴用数学式子表示为（2n+1）2-（2n-1）2=（2n+1+2n-1）（2n+1-2n+1）=4n×2=8n．
故答案为：（2n+1）2-（2n-1）2=8n．
| 阅读下列各小题，根据汉语提示，用句末括号内的英语单词完成句子。 1. when you deal with this chemical,as it will explode when __________________. (expose) 处理这种化学物质时要小心,因为它暴露在阳光下时会爆炸. 2. Nowadays young people just can't live without the Internet, _______________for whatever information they need. (depend) 如今的年轻人离开因特网就无法生活,他们依靠它获取自己所需信息. 3. A hobby is what you never get tired of - ____________________, the more fun you will have. (devote) 爱好是不会让你感到厌倦的- 你投入的时间越多,获得的乐趣越多.. 4. So______________________________ on the phone that we knew there would be good news. (voice) 他的声音在电话中听起来如此地激动,以至于我们都知道会有好消息. 5. Part of the reason why he is absent is , I think, that he __________________the meeting.(inform) 我想他缺席会议的部分原因是他可能没被通知. 6. ___________________________________, professor Smith went straight to the laboratory to continue his experiments.(have) 理完发后,Smith 教授径直到了实验室,继续他的实验. 7. Whatever you have picked up, you should give it back to_____________________.(belong) 无论你捡到什么东西,你都应该物归原主. 8. Her father gave her advice on learning English _________________________________as much as possible.(employ) 她的父亲建议她学英语时尽可能多用它. 9. We are designing an experiment to find out if __________________________________ when it is cold.(break) 我们正在设计一个实验,想弄清楚当天冷时,玻璃是否更容易破裂. 10. _____________________ she is not so cheerful as she used to be?(why) 她没有以前那么高兴究竟是为什么呢? |