Question

help bài 6 =))

Answer 1

Bài 6

a)\(A=\dfrac{15}{16}+\dfrac{13}{33}+\dfrac{1}{11}+\dfrac{7}{33}+\dfrac{-15}{16}+\dfrac{20}{66}\)

       \(=\dfrac{15}{16}+\dfrac{13}{33}+\dfrac{3}{33}+\dfrac{7}{33}+\dfrac{-15}{16}+\dfrac{10}{33}\)

       \(=\left(\dfrac{15}{16}+\dfrac{-15}{16}\right)+\left(\dfrac{13}{33}+\dfrac{3}{33}+\dfrac{7}{33}+\dfrac{10}{33}\right)\)

       \(=0+1=1\)

b)\(B=\dfrac{1}{3}+\dfrac{-3}{4}+\dfrac{3}{5}+\dfrac{-1}{36}+\dfrac{1}{15}+\dfrac{-2}{9}\)

       \(=\dfrac{5}{15}+\dfrac{-27}{36}+\dfrac{9}{15}+\dfrac{-1}{36}+\dfrac{1}{15}+\dfrac{-8}{36}\)

       \(=\left(\dfrac{5}{15}+\dfrac{9}{15}+\dfrac{1}{15}\right)+\left(\dfrac{-27}{36}+\dfrac{-1}{36}+\dfrac{-8}{36}\right)\)

       \(=1-1=0\)

c)\(C=\dfrac{1}{2}+\dfrac{-2}{3}+\dfrac{3}{4}+\dfrac{-4}{5}+\dfrac{5}{6}+\dfrac{-5}{6}+\dfrac{4}{5}+\dfrac{-3}{4}+\dfrac{2}{3}+\dfrac{-1}{2}\)

        \(=\left(\dfrac{1}{2}+\dfrac{-1}{2}\right)+\left(\dfrac{-2}{3}+\dfrac{2}{3}\right)+\left(\dfrac{3}{4}+\dfrac{-3}{4}\right)+\left(\dfrac{-4}{5}+\dfrac{4}{5}\right)+\left(\dfrac{5}{6}+\dfrac{-5}{6}\right)\)

\(=0+0+0+0+0=0\)