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已知等差数列前9项的和为27,,则A.100 B.99 C.98 D.97
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已知等差数列前9项的和为27,,则( )
A.100 B.99 C.98 D.97
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已知数列{an}和{bn}都是等差数列,a1=25,b1=75且a100+b100=100,则数列{an+bn}的前10项和是( )
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设等差数列an的前n项之和为Sn,已知S10=100,则a4+a7=( )
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设等差数列an的前n项之和为Sn,已知S10=100,则a4+a7=( )
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设等差数列an的前n项之和为Sn,已知S10=100,则a4+a7=( )
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A.12
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设等差数列an的前n项之和为Sn,已知S10=100,则a4+a7=( )
A.12
B.20
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设等差数列an的前n项之和为Sn,已知S10=100,则a4+a7=( )
A.12
B.20
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已知正项等差数列{an}的前20项和为100,则a5•a16的最大值是( )
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