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职教组卷
  • 题型:解答题 题类:月考试卷 难易度:难

    已知数列\(\{a _{n} \}\)满足\(a _{n+2} +a _{n} =2a _{n+1} (n∈N ^{*} )\),数列\(\{b _{n} \}\)满足\(\dfrac{{{b}_{n+1}}}{{{b}_{n}}}={{a}_{n+1}}-{{a}_{n}} (n∈N ^{*} )\),且\(a _{1} =b _{1}\),\(a _{3} =5\),\(a _{5} +a _{7} =22\).

    \((1)\)求\(a _{n}\)及\(b _{n}\);

    \((2)\)令\(c _{n} =a _{n} b _{n}\),\(n∈N ^{*}\),求数列\(\{c _{n} \}\)的前\(n\)项和\(S _{n}\).

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