数列求和练习(奇偶项)

nn19919899nn12100n243nn32+2nnn*nnn2*n1*nnn*nn25nnnnn19919899nn12100n243nn32+2nnn*nnn2*n1*nnn*nn25nnnnnnnnnn413nnnn数列综合奇偶项）一选题共1小题）{}qnaa0

＜q11aaT1n199A

B

C

D二填题共1小题）

当为数时当偶数时

f+f+1+a+a++三解题共小题{}a3aa1{}221N*

}nTT{}nkN

9k{}{}n+1{}a2nN

2{}TTmNmS{}{}n2nN{}{}

，，

{n

}n{}nS1{}2{}

b1

3

n

{}a1{

，}

N*第页（共页）nnnnnnnnnnk11231nkkn12k+1k35nn1n2*n2*2nnnnn1n12nnnnnnnnnnk11231nkkn12k+1k35nn1n2*n2*2nnnnn1n12nn25nnn30n2n+1nnn1nnn+1nn2nnnnn22{}{}n

{}{n+2}{}0{}kk++{}+1aak13﹣a{}为偶数{}a

n

为奇数

1

nNa

﹣

1

Na{}{}T{}na0a1{}2++{}430{}{}30T{}3a﹣{}{}

，求

n

{}2+331{}2{}2T{}n

{n

}

{}{}{}2T第页（共页）nn1424nnnnnnn1125nnn2n35nn1424nnnnnnn1125nnn2n35nnnnn2nnnnnnnnn1n10{}nI{}{}为奇数

2a12SII

c

为偶数

T{}n{}Sa1{}

S102b

，为数{}2n+1，为数{}a{}{}2S{}a1N*{}

nN*{}1

2{}10第页（共页）21979829910011119899100198+19799…99100299100nnn+1123100134992n2421979829910011119899100198+19799…99100299100nnn+1123100134992n24n1n1﹣n+1n3n+23n*n11n1参考答案与试题解析一选题共1小题）aa1aq1a1

＜a110q1TaaaD二填题共1小题）

qaa11

an+f+1

是奇数是偶数a

+a2a++a+aa++a+a++a2+2+2++2100三解题共小题{}q0a23q29qq{}3a

13nN*22n1nlog321

n

1

1

12kNkanaa272

n

5n︸

3a+13

第页（共页）n532n11n1n1nnnnnnn1nnnnn13111nn+1n13n1nn532n11n1n1nnnnnnn1nnnnn13111nn+1n13n1n

＜

{}a

2a+nn1

T11

T2b﹣﹣b1bbb2{}2﹣﹣2B

}dnS32a32a+78d52a12n2bb+bbb﹣+2n+1n2n+4nT1

，

{

}1

21

1

第页（共页）1n+1nnnn1n12n1k21111n1﹣1n1n1﹣nn1﹣12nn1223435435IIa+11n+1nnnn1n12n1k21111n1﹣1n1n1﹣nn1﹣12nn1223435435IIa+13+12ak﹣32k+1k12a33kkk﹣2+13kkakkk﹣nn+1

a2{}221{}b2n124b[2﹣

4{}adaa2d

+k1aa

k2

k++1+3++3

n2n

1110a3a+4a13kkk2+1k1

1k

3

3+

k1

1

﹣

a

1k

﹣

a

1

+[1（++1]aa

[1]a22k1

111{}nan

n，

2

{

n

}3n+1

2第页（共页）n+1n+1nn221nn2nnn5111nnnn30n12n1nnnn1nnn1n1﹣23n123n1﹣n23nn+1n+1nn221nn2nnn5111nnnn30n12n1nnnn1nnn1n1﹣23n123n1﹣n23n1nnnnnnn1n1nn1n111nnnnn+a0a1012a

aa1{}a+12an+1n5+9+13++40372039189{}S30+d4b+10d2nN*

，为数{}T6154+8+，为数

30

154+60240a}a4a3﹣aa3a33a13﹣﹣{}a3aa3aa3﹣

a+aa+aa+1+3+3+﹣

nn

n

[1+2+++1+n]

n

n

[+5+6+++2+nn]

n

，为数，为数aaa2

1

na22a2﹣﹣﹣a2{}{}

n

2bn第页（共页）nnnnn+1nnn1424234343nnnnn23224n11nn35711n1nnnn+1213n2nn11nn1nn1nnnnnn+1nnn1424234343nnnnn23224n11nn35711n1nnnn+1213n2nn11nn1nn1nn1n﹣nnII{}n

1n+13+4n22

2+{}S

d

t+n1

tnba12SSStq12a22a

2b2c

为奇数为偶数

c

，为数，偶数T+

1

+cc[]+1

a

3

，

21

，奇数，为数{}2n+1{}a+26ad2adn2ba12+3b++bb5+5741+4+