已知数列{An}是各项均不为0的等差数列,Sn为其前n项和,满An=S2n-1(n为正整数）,若不等式k/An+1

Question

已知数列{An}是各项均不为0的等差数列,Sn为其前n项和,满An=S2n-1(n为正整数）,若不等式k/An+1

Answer 1

把你标上红括号的前一式子左右两边分子分母都颠倒一下得(4m²+4m+1)/m²=(6n+3)/n把右边拆成两项 (4m²+4m+1)/m²=6 +(3/n)移项得3/n=(4m²+4m+1)/m² - 6右边通一下分就得3/n=(-2m²+4...