2022年山西英语周报初中xin答案

因为a1,a3,S5成等比数列,所以a2=a1S5即(a1 2d)2=a1(5a1 10d),又a2=a1 d=32分解得(舍去),分所以1 2(n-1)=2n-15分(2)由(1)可得bn=2· . 3=2- n 15=2-1 (-n 分所以T 2 … 2- (1-) (- (2-n-2=#2 1-n-2 n10分17.【解析】(1)设等差数列{an}的公差为d(d>0),

Paragraph IJatin looked up and he saw the other boys rushingahead. Refusing to give up at this crucial point, Jatinclenched his teeth, jumped to his feet and ran as fast as hecould. Finally, he was the fourth one to dash across thefinish line. Jatin couldnt help sobbing at the thought ofletting his sister down. But much to his surprise, the run-ner who collided with him was disqualified for breaking therule and Jatin won the third prize. Jatin felt overjoyed andrelieved during the award ceremony, holding the shoesclose to his chestParagraph 2Filled writh pleasure, Jatin walked home in no timeHe could not wait to see his sister and share the good newsOn his arrival, Jatin found Neha was walking about outsidnervously and anxiously. " Neha, see what I have got foryou.Jatin said excitedly, taking the prize out of his bagwith his trembling hands. The instant Neha saw the shoesher face lit up. So thrilled was she that she threw herself atJatin."Thank you! Jatin. " Tears of joy welled up in theieyes as the brother and the sister hugged tightly together

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