(x+2)+(x+4)+(x+6)+...+(x+100)=6000
1+2+3+4+...+x=15
x-(\(\frac{20}{11.13}\)+ \(\frac{20}{13.15}\)+\(\frac{20}{15.17}\)+...+\(\frac{20}{53.55}\))=\(\frac{3}{11}\)
\(\frac{7}{4}\)x. (\(\frac{33}{12}\)+ \(\frac{3333}{2020}\)+ \(\frac{333333}{303030}\)+ \(\frac{33333333}{42424242}\)) = 42
\(\frac{1}{3}+\frac{1}{6}+\frac{1}{10}+\frac{1}{15}+...+\frac{2}{x\left(x-1\right)}\)= \(\frac{2007}{2009}\)
\(\left(\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}+\frac{1}{28}+\frac{1}{256}\right)\).x=1