AT

tính

\(A=\dfrac{-3}{17}+\left(\dfrac{2}{3}+\dfrac{3}{17}\right)\)

\(B=\left(\dfrac{-1}{6}+\dfrac{5}{12}\right)+\dfrac{7}{12}\)

\(C=-\dfrac{5}{7}+\dfrac{3}{4}+\dfrac{-1}{5}+\dfrac{-2}{7}+\dfrac{1}{4}\)

H24
4 tháng 2 lúc 8:45

\(A=\dfrac{-3}{17}+\left(\dfrac{2}{3}+\dfrac{3}{17}\right)\)

\(=\left(\dfrac{-3}{17}+\dfrac{3}{17}\right)+\dfrac{2}{3}\)

\(=\dfrac{2}{3}\)

\(---\)

\(B=\left(\dfrac{-1}{6}+\dfrac{5}{12}\right)+\dfrac{7}{12}\)

\(=\dfrac{-1}{6}+\left(\dfrac{5}{12}+\dfrac{7}{12}\right)\)

\(=\dfrac{-1}{6}+1\)

\(=\dfrac{-1}{6}+\dfrac{6}{6}=\dfrac{5}{6}\)

\(---\)

\(C=-\dfrac{5}{7}+\dfrac{3}{4}+\dfrac{-1}{5}+\dfrac{-2}{7}+\dfrac{1}{4}\)

\(=\left(\dfrac{-5}{7}+\dfrac{-2}{7}\right)+\left(\dfrac{3}{4}+\dfrac{1}{4}\right)+\dfrac{-1}{5}\)

\(=\left(-1\right)+1-\dfrac{1}{5}\)

\(=-\dfrac{1}{5}\)

\(\text{#}Toru\)

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