观察下列各式:a+b+1=2,a2+b2+2=5,a3+b3+3=7,a4+b4+4=11,a5+b5+5=16,…,则a10+b10+10=_______.

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问题 观察下列各式:a+b+1=2,a2+b2+2=5,a3+b3+3=7,a4+b4+4=11,a5+b5+5=16,…,则a10+b10+10=_______.

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答案133

解析 依题中规律可得:a+b=1,a2+b2=3,a3+b3=4,a4+b4=7,a5+b5=11,…,令Sn=an+bn,易得Sn+2=Sn+Sn+1,从而S6=18,S7=29,S8=47,S9=76,S10=123,所以a10+b10+10=133.
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