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a) \(\frac{3}{16}+\frac{4}{15}+\frac{5}{16}+\frac{1}{15}\)
\(=\left(\frac{3}{16}+\frac{5}{16}\right)+\left(\frac{4}{15}+\frac{1}{15}\right)\)
\(=\frac{1}{2}+\frac{1}{3}\)
\(=\frac{5}{6}\)
b) \(\frac{6}{7}\times\frac{8}{15}\times\frac{7}{6}\times\frac{15}{16}\)
\(=\left(\frac{6}{7}\times\frac{7}{6}\right)\times\left(\frac{8}{15}\times\frac{15}{16}\right)\)
\(=1\times\frac{1}{2}=\frac{1}{2}\)
c) \(\frac{19}{20}\times\frac{13}{21}+\frac{9}{20}\times\frac{8}{21}\)
\(=\frac{19\times13}{20\times21}+\frac{9\times8}{20\times21}\)
\(=\frac{247}{420}+\frac{72}{420}\)
\(=\frac{319}{420}\)
giúp mình đi khi nào bạn làm đúng thì mình sẽ thả like cho bạn
( 1- \(\dfrac{1}{15}\))x ( 1 - \(\dfrac{1}{16}\))x(1- \(\dfrac{1}{17}\)) x.....x(1- \(\dfrac{1}{100}\))
= \(\dfrac{14}{15}\) x \(\dfrac{15}{16}\)x \(\dfrac{16}{17}\)x......x\(\dfrac{99}{100}\)
= \(\dfrac{15\times16\times17\times.....\times99}{15\times16\times17\times.....\times99}\) x \(\dfrac{14}{100}\)
= 1 x \(\dfrac{14}{100}\)
= \(\dfrac{7}{50}\)
( 1 + 1/13 ) x ( 1 + 1/14 ) x ( 1 + 1/15 ) x ( 1 + 1/16 ) x ( 1 + 1/17 )
= 14/13 x 15/14 x 16/15 x 17/16 x 18/17
= 18/13
\(\left(1+\frac{1}{15}\right).\left(1+\frac{1}{16}\right).\left(1+\frac{1}{17}\right).\left(1+\frac{1}{18}\right)\)
=\(\frac{16}{15}.\frac{17}{16}.\frac{18}{17}.\frac{19}{18}\)
=\(\frac{19}{15}\)