设数列an,bn都是等差数列若a1+b1=5 a7+b7=15则a4+b4=
设数列an,bn都是等差数列若a1+b1=5 a7+b7=15则a4+b4=
有两个等差数列{an},{bn},满足a1+a2+…+an/(b1+b2+…+bn)=5n/(3n+6),则a7/b7=
设数列an是等差数列,bn为等比数列,若a1=b1=1,a2+a4=b3,b2×b4=a3,求数列an,bn的通项公式
两个等差数列{an},{bn},a1+a2+...+an/b1+b2+...+bn=7n+2/n+3,求a7/b7?急,
设等差数列{an}的公差与等比数列{bn}的公比都是d,d≠1,a1=b1,a4=b4,a10=b10
已知{an}是等差数列 满足a1=3 a4=12 数列{bn}满足b1=4 b4=20 且{bn-an}为等比数列.
等差数列{an}等比数列{bn}其中a1=b1 a2=b2 a4=b4 两数列公差公比都为d 求{an}{bn}
设{an}为等差数列,{bn}为等比数列又a1=b1,a3=b3,a7=b5.比较的a15和b7大小关系,给出证明
已知数列{an},{bn}都是公差为1的等差数列,其首项分别为a1,b1,且a1+b1=5,a1,b1∈N*,设c
设{an},{bn}分别为等差数列与等比数列,且a1=b1=4,a4=b4=1,则以下结论正确的是( )
设数列{an}和{bn}都是等差数列,且a1=25,b1=75,a100+b100=100,则数列{an+bn}的前10
设数列{an}和{bn}都是等差数列,其中a1=25,b1=75,且a100+b100=100,则数列{an+bn}的前