Question

Tính :

a) 3/5 + 5/7 = .......................... ;                            3/4 + 5/6 = ...........................

    3/4 + 2 5/7 = ....................... ;                            1 3/4 + 7 5/6 = ......................

b) 19/12 - 3/4 = ....................... ;                            19/12 - 5/6 = ........................

    1 11/35 - 5/7 = ..................... ;                            7 19/12 - 4 5/6 = ..................

Answer 1

a) \(\dfrac{3}{5}+\dfrac{5}{7}=\dfrac{21}{35}+\dfrac{25}{35}=\dfrac{46}{35}\)

\(\dfrac{3}{4}+\dfrac{5}{6}=\dfrac{9}{12}+\dfrac{10}{12}=\dfrac{19}{12}\)

\(\dfrac{3}{4}+2\dfrac{5}{7}=\dfrac{3}{4}+\dfrac{19}{7}=\dfrac{21}{28}+\dfrac{76}{28}=\dfrac{97}{28}\)

\(1\dfrac{3}{4}+7\dfrac{5}{6}=\dfrac{7}{4}+\dfrac{47}{6}=\dfrac{21}{12}+\dfrac{94}{12}=\dfrac{115}{12}\)

b) \(\dfrac{19}{12}-\dfrac{3}{4}=\dfrac{19}{12}-\dfrac{9}{12}=\dfrac{10}{12}=\dfrac{5}{6}\)

\(\dfrac{19}{12}-\dfrac{5}{6}=\dfrac{19}{12}-\dfrac{10}{12}=\dfrac{9}{12}=\dfrac{3}{4}\)

\(1\dfrac{11}{35}-\dfrac{5}{7}=\dfrac{35}{35}+\dfrac{11}{35}-\dfrac{25}{35}=\dfrac{21}{35}=\dfrac{3}{5}\)

\(7\dfrac{19}{12}-4\dfrac{5}{6}=\dfrac{103}{12}-\dfrac{29}{6}=\dfrac{103}{12}-\dfrac{58}{12}=\dfrac{45}{12}=\dfrac{15}{4}\)

 

Answer 2

a) \(\dfrac{3}{5}+\dfrac{5}{7}=\dfrac{21}{35}+\dfrac{25}{35}=\dfrac{46}{35};\dfrac{3}{4}+2\dfrac{5}{7}=\dfrac{3}{4}+\dfrac{19}{7}=\dfrac{21}{28}+\dfrac{76}{28}=\dfrac{97}{28}\)

b) \(\dfrac{19}{12}-\dfrac{3}{4}=\dfrac{19}{12}-\dfrac{9}{12}=\dfrac{10}{12}=\dfrac{5}{6};1\dfrac{11}{35}-\dfrac{5}{7}=\dfrac{46}{35}-\dfrac{25}{35}=\dfrac{21}{35}=\dfrac{3}{5}\)

c) \(\dfrac{3}{4}+\dfrac{5}{6}=\dfrac{9}{12}+\dfrac{10}{12}=\dfrac{19}{12};1\dfrac{3}{4}+7\dfrac{5}{6}=\dfrac{7}{4}+\dfrac{47}{6}=\dfrac{21}{12}+\dfrac{94}{12}=\dfrac{115}{12}\)

d) \(\dfrac{19}{12}-\dfrac{5}{6}=\dfrac{19}{12}-\dfrac{10}{12}=\dfrac{9}{12}=\dfrac{3}{4};7\dfrac{19}{12}-4\dfrac{5}{6}=\dfrac{103}{12}-\dfrac{29}{6}=\dfrac{103}{12}-\dfrac{58}{12}=\dfrac{45}{12}=\dfrac{15}{4}\)

Answer 3

1.

a) 3/5 + 5/7 = 21/35 + 25/35 = 46/35

    3/4 + 2 5/7 = 3/4 + 19/7 = 21/28 + 76/28 = 97/28

b) 19/12 - 3/4 = 19/12 - 9/12 = 10/12

     1 11/35 - 5/7 = 9/7 - 5/7 = 4/7

 3/4 + 5/6 = 9/12 + 10/12 = 19/12

1 3/4 + 7 5/6 = 7/4 + 47/6 = 21/12 + 94/12 = 115/12

19/12 - 5/6 = 19/12 - 10/12 = 9/12 = 3/4

7 19/12 - 4 5/6 = 103/12 - 29/6 = 103/12- 58/12 = ....../........