標題:
sequence
發問:
If the first term of an arithmetic sequence is 7 and the sum of the first 10 terms is 325,find the 10th term. 更新: find the sum of the first 10 terms of an arithmetic sequence if its 4th term is 10 and the common difference is 2.
1. If the first term of an arithmeticsequence is 7 and the sum of the first 10 terms is 325，find the 10thterm. Sol a1=7 S10=(a1+a10)*10/2 325=(7+a10)*5 a10=58 2. find the sum of the first 10 terms of an arithmetic sequence if its 4th termis 10 and the common difference is 2. Sol a4=a1+3d 10=a1+3*2 a1=4 a10=a1+9d=4+18=22 S10=(a1+a10)*10/2=(4+22)*5=130
其他解答:4E350C6F8B48ECA2
sequence
發問:
If the first term of an arithmetic sequence is 7 and the sum of the first 10 terms is 325,find the 10th term. 更新: find the sum of the first 10 terms of an arithmetic sequence if its 4th term is 10 and the common difference is 2.
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最佳解答:1. If the first term of an arithmeticsequence is 7 and the sum of the first 10 terms is 325，find the 10thterm. Sol a1=7 S10=(a1+a10)*10/2 325=(7+a10)*5 a10=58 2. find the sum of the first 10 terms of an arithmetic sequence if its 4th termis 10 and the common difference is 2. Sol a4=a1+3d 10=a1+3*2 a1=4 a10=a1+9d=4+18=22 S10=(a1+a10)*10/2=(4+22)*5=130
其他解答:4E350C6F8B48ECA2
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