Bài 2:
\(a,\dfrac{2\times6\times13}{5\times13\times6}=\dfrac{2}{5}\\ b,\dfrac{8\times11\times13}{11\times13\times16}=\dfrac{8}{16}=\dfrac{8}{8\times2}=\dfrac{1}{2}\\ c,\dfrac{5\times18\times12}{15\times24\times16}=\dfrac{5\times3\times3\times6\times3\times4}{3\times5\times4\times6\times4\times4}=\dfrac{3\times3}{4\times4}=\dfrac{9}{16}\\ d,\dfrac{15\times8\times4}{32\times3\times5}=\dfrac{5\times3\times8\times4}{4\times8\times3\times5}=\dfrac{1}{1}=1\)
Bài 1:
\(a,\dfrac{8}{12}=\dfrac{8:4}{12:4}=\dfrac{2}{3}\\ \dfrac{20}{48}=\dfrac{20:4}{48:4}=\dfrac{5}{12}\\ \dfrac{74}{100}=\dfrac{74:2}{100:2}=\dfrac{37}{50}\\ \dfrac{18}{21}=\dfrac{18:3}{21:3}=\dfrac{6}{7}\\ \dfrac{40}{54}=\dfrac{40:2}{54:2}=\dfrac{20}{27}\\ \dfrac{30}{45}=\dfrac{30:15}{45:3}=\dfrac{2}{3}\\ b,\dfrac{18}{24}=\dfrac{18:6}{24:6}=\dfrac{3}{4}\\ \dfrac{49}{28}=\dfrac{49:7}{28:7}=\dfrac{7}{4}\\ \dfrac{15}{35}=\dfrac{15:5}{35:5}=\dfrac{3}{7}\\ \dfrac{28}{40}=\dfrac{28:4}{40:4}=\dfrac{7}{10}\\ \dfrac{36}{27}=\dfrac{36:9}{27:9}=\dfrac{4}{3}\\ \dfrac{56}{49}=\dfrac{56:7}{49:7}=\dfrac{8}{7}\)
\(c,\dfrac{85}{51}=\dfrac{85:17}{51:17}=\dfrac{5}{3}\\ \dfrac{1515}{2323}=\dfrac{1515:101}{2323:101}=\dfrac{15}{23}\\ \dfrac{39}{26}=\dfrac{39:13}{26:13}=\dfrac{3}{2}\\ \dfrac{323232}{515151}=\dfrac{323232:10101}{515151:10101}=\dfrac{32}{51}\)
