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1 安徽五河二中 卜盛淼 (邮编:2 3 3 0 0 0 )题 已知limn→∞( 6an-bn) =7,limn→∞( 3an-4bn) =-1 ,求limn→∞( 3an+bn)的值。解 由数列极限四则运算法则得:6limn→∞an-limn→∞bn=7①3limn→∞an-4limn→∞bn=-1②解①②得limn→∞an=2 92 1 , limn→∞bn=97,∴limn
1 Wu Sheng Erzhong, Anhui Bu Shengjun (Zip Code: 2 3 3 0 0 0) known limn → ∞ (6an-bn) = 7, limn → ∞ (3an-4bn) =-1, seeking limn → ∞ (3an+ The value of bn). The solution consists of a sequence of four rules: 6limn→∞an-limn→∞bn=713limn→∞an-4limn→∞bn=-12 Solution 12: Limn→∞an=2 92 1 ,limn→∞bn=97 ∴limn