設S1=12,S2=12+22+12,S3=12+22+32+22+12,…,Sn=12+22+…+n2+…+22+12,…,某學生猜測Sn=n(an2+b),老師:回答正確,則a+b=_.
設S1=12,S2=12+22+12,S3=12+22+32+22+12,…,Sn=12+22+…+n2+…+22+12,…,某學生猜測Sn=n(an2+b),老師:回答正確,則a+b=______.
數(shù)學人氣:809 ℃時間:2020-04-12 10:22:11
優(yōu)質(zhì)解答
∵S
1=1
2=1×(
×1
2+
),
S
2=1
2+2
2+1
2=2×(
×2
2+
),
S
3=1
2+2
2+3
2+2
2+1
2=3×(
×3
2+
),
…,
由此我們可以推斷
S
n=1
2+2
2+…+n
2+…+2
2+1
2=n×(
×n
2+
),
故a=
,b=
,
∴a+b=1
故答案為:1
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