21.解:本题考查数列的通项与求和(1)证明::2a1+2b1=a.-3+b.-3,∴:an+1+b+1+6=(an+bn+6),∵a1+b1+6=0,∴an+b+6=0,即an+bn=-6.6分(2)∵2an+1-2b2+1=b-an,即bx+1-an+1(bn-an),b-a1=8,--=8(2),又a+b-6…:2=-6+8·(-2)”即b=-3+4·(12分

Dear JackIm glad to know that you are paying more attention toyour health and' planning to take part in a fitness project. Ithink it is wise of you to do so because nothing ismoreimportant than health in the world. Without health, we canhardly live a happy lifeAs to the way to keep"fit, I suggest you shouldplaying table tennis. It can not only get your musclesinvolved when you play but also benefit your eyesightWhat's more, it can improve your balance and keep yourbrain sharp. So I'm sure you can be much stronger bypracticing itLooking forward to receiving your good newsYours sincerelyLi Hu

以上就是2021-2022七下英语周报第38期答案，更多英语周报答案请关注本网站。

本文地址： http://www.ncneedu.cn/post/10285.html

文章来源：admin

版权声明：除非特别标注，否则均为本站原创文章，转载时请以链接形式注明文章出处。