a) a_{k}= \frac{1+ (-1)^{k} }{k}
a_{1}= \frac{1+ (-1)^{1} }{1}=0
a_{3}= \frac{1+ (-1)^{3} }{3}= \frac{1-1}{3}=0
a_{10}= \frac{1+(-1)^{10} }{10}= \frac{1+1}{10}= \frac{2}{10}=0,2
b) a_{k}= (1+ \frac{1}{k} )^{k}
a_{1}= (1+ \frac{1}{1}) ^{1}= 2^{1} =2
a_{3}= (1+ \frac{1}{3} )^{3}= ( \frac{4}{3} )^{3}= \frac{64}{27}= 2 \frac{10}{27}
a_{10}= (1+ \frac{1}{10} )^{10}= ( \frac{11}{10} )^{10}