Question: Find the sum of each of the convergent series given below

a- \(\sum\limits_{k=1}^{\infty }{\left( \frac{1}{{{2}^{k}}}-\frac{1}{{{2}^{k+1}}} \right)}\)

b- \(\sum\limits_{k=2}^{\infty }{\left( \frac{1}{{{k}^{2}}-1} \right)}\)

c- \(\sum\limits_{n=5}^{\infty }{{{\left( \frac{e}{\pi } \right)}^{n-1}}}\)