CM

\(\dfrac{1}{5}< \dfrac{1}{4^2}+\dfrac{1}{5^2}+...+\dfrac{1}{100^2}< \dfrac{1}{3}\)

so sanh

M=\(\left(\dfrac{1}{2^2}-1\right).\left(\dfrac{1}{3^2}-1\right).\left(\dfrac{1}{4^2}-1\right)...\left(\dfrac{1}{100^2}-1\right)\)va \(\dfrac{1}{2}\)

B=\(\dfrac{1}{20}+\dfrac{1}{21}+...+\dfrac{1}{200}va\dfrac{9}{10}\)

C=\(\dfrac{10}{17}+\dfrac{8}{15}+\dfrac{11}{16}va2\)

tinh nhanh

B=\(\dfrac{3}{1^{2^{ }}.2^2}+\dfrac{5}{2^2.3^2}+\dfrac{7}{3^{2^{ }}.4^2}+...+\dfrac{19}{9^2.10^2}\)

tinh nhanh

\(\dfrac{-2}{5}.\left(\dfrac{5}{17}-\dfrac{9}{15}\right)-\dfrac{2}{5}.\left(\dfrac{2}{17}+\dfrac{-2}{5}\right)\)

tinh nhanh

\(\dfrac{25}{100}+\dfrac{14}{21}-\dfrac{31}{62}-\dfrac{-15}{40}+\dfrac{-27}{45}-\dfrac{-36}{135}\)

tinh nhanh

\(\left(1-\dfrac{28}{10}\right).\left(1-\dfrac{52}{22}\right).\left(1-\dfrac{80}{36}\right)....\left(1-\dfrac{21808}{10900}\right)\)

tinh nhanh\(\left(1-\dfrac{1}{21}\right).\left(1-\dfrac{1}{28}\right)....\left(1-\dfrac{1}{1326}\right)\)

so sanh = cach hop li

a, \(\dfrac{7}{15}va\dfrac{20}{39}\)

b,\(\dfrac{14}{41}va\dfrac{17}{53}\)

c, \(\dfrac{4^{100^{ }}+2}{4^{98}-1}va\dfrac{4^{98^{ }}+2}{4^{96}-1}\)

so sanh = cach hop li

\(\dfrac{4^{100^{ }}+2}{4^{98^{ }}-1}va\dfrac{4^{98^{ }}+2}{4^{96^{ }}-1}\)

1, so sanh = cach hop li

a,\(\dfrac{31}{67}va\dfrac{29}{73}\)