Bài tập 76 trang 39 SGK Toán 6 Tập 2

\(A= \frac{7}{19}.\left (\frac{8}{11}+\frac{3}{11} \right )+\frac{12}{19}=\frac{7}{19}.1 +\frac{12}{19}=1\).

\(B=\frac{5}{9}.\left (\frac{7}{13}+\frac{9}{13}-\frac{3}{13} \right )=\frac{5}{9}.\frac{7+9-3}{13}=\frac{5}{9}.\frac{13}{13}=\frac{5}{9}.\)

\(C=\left (\frac{67}{111}+\frac{2}{33}-\frac{15}{117} \right ).\left (\frac{1}{3}-\frac{1}{4}-\frac{1}{12} \right )\)

\(=\left (\frac{67}{111}+\frac{2}{33}-\frac{15}{117} \right ).\frac{4-3-1}{12}=\left (\frac{67}{111}+\frac{2}{33}-\frac{15}{117} \right ).0=0\)

-- Mod Toán 6 HỌC247