For all integers n ≥ 2, show
Sigma(1/(n+1))> (13/24)
P.S. Above the sigma is and underneath it is i=1.
It still doesn't make sense. What is $\displaystyle i$? What is the upper limit of the summation? Please try to write out the original question.
Meanwhile, note that $\displaystyle \frac{1}{3} + \frac{1}{4} = \frac{7}{12}>\frac{13}{24}$, if that is any help.
Grandad