已知{an}为等差数列,且a1+a3=8,a2+a4=12.则an=______.
已知{an}为等差数列,且a1+a3=8,a2+a4=12.则an=______.
已知等差数列{an},若a1+a3+a5=9,则a2+a4=______.
已知{an}为等差数列,a1+a3+a5=105,a2+a4+a6=99,则a20=______.
已知数列an为等差数列,an=n,则a1*a2-a2*a3+a3*a4-a4*a5+...-a100*a101=
等差数列{an}中,a1+a2=20,a3+a4=80,则S10=______.
设{an}是一个公差为1的等差数列,且a1+a2+a3+…+a98=137,则a2+a4+a6+…a98=______.
设数列{an}是等差数列,若a3+a4+a5=12,则a1+a2+…+a7=______.
已知等比数列{An},a1=3,且4a1 2a2 a3成等差数列,则a3+a4+a5等于?
已知数列{an}为等差数列,a1+a2+a3=6,a7+a8+a9=24,则a4+a5+a6=______.
已知等差数列(an)的公差为2,若a1,a3,a4成等比则a2=?
已知等差数列{an}的公差为3,若a1,a3,a4成等比数列,则a2=
已知等差数列{an}的公差为2,若a1,a3,a4成等比数列,则a2=?