Question

 Giúpp gấp lắm roii, 8h em nộp bài roii

Answer 1

1;  \(\dfrac{7}{15}\) + \(\dfrac{8}{15}\) = \(\dfrac{7+8}{15}\) = \(\dfrac{15}{15}\) = 1

2; \(\dfrac{1}{2}\) - \(\dfrac{1}{14}\) = \(\dfrac{1.7}{2.7}\) - \(\dfrac{1}{14}\) = \(\dfrac{7-1}{14}\) = \(\dfrac{6}{14}\) = \(\dfrac{3}{7}\)

3; \(\dfrac{8}{28}\) + \(\dfrac{-21}{35}\) = \(\dfrac{2}{7}\) + \(\dfrac{-21}{35}\)= \(\dfrac{10}{35}\) + \(\dfrac{-21}{35}\) = \(\dfrac{-11}{35}\)

Answer 2

4; \(\dfrac{3}{4}\) + \(\dfrac{2}{3}\) - \(\dfrac{9}{6}\)  = \(\dfrac{9}{12}\) + \(\dfrac{8}{12}\) - \(\dfrac{18}{12}\) = \(\dfrac{9+8-18}{12}\) = \(\dfrac{-1}{12}\)

5; \(\dfrac{11}{36}\)- \(\dfrac{-7}{-24}\) = \(\dfrac{22}{72}\) + \(\dfrac{21}{72}\) = \(\dfrac{53}{72}\)

6; \(\dfrac{4}{15}\) + \(\dfrac{9}{5}\) - \(\dfrac{7}{3}\) = \(\dfrac{4}{15}\) + \(\dfrac{27}{15}\) - \(\dfrac{35}{15}\) = \(\dfrac{-4}{15}\) 

Answer 3

7; \(\dfrac{7}{5}\) + \(\dfrac{2}{3}\) - \(\dfrac{7}{10}\) = \(\dfrac{42}{30}\) + \(\dfrac{20}{30}\) - \(\dfrac{21}{30}\) = \(\dfrac{41}{30}\)

8; \(\dfrac{-5}{6}\) + \(\dfrac{2}{3}\) - \(\dfrac{1}{8}\) = \(\dfrac{-20}{24}\) + \(\dfrac{16}{24}\) - \(\dfrac{3}{24}\)= \(\dfrac{-7}{24}\)

9; \(\dfrac{3}{4}\) - \(\dfrac{2}{3}\) + \(\dfrac{-7}{12}\) = \(\dfrac{9}{12}\) - \(\dfrac{8}{12}\) + \(\dfrac{-7}{12}\) = \(\dfrac{-6}{12}\) = \(\dfrac{-1}{2}\)

Answer 4

10; \(\dfrac{1}{5}\) + \(\dfrac{2}{5}\) - \(\dfrac{7}{10}\) = \(\dfrac{3}{5}\) - \(\dfrac{7}{10}\) = \(\dfrac{6}{10}-\dfrac{7}{10}\) = - \(\dfrac{1}{10}\)

11; \(\dfrac{15}{27}\).\(\dfrac{9}{5}\) - \(\dfrac{1}{2}\) = 1 - \(\dfrac{1}{2}\) = \(\dfrac{1}{2}\)

Answer 5

12; \(\dfrac{-3}{4}\).(\(\dfrac{1}{2}\) - \(\dfrac{2}{3}\))

=  - \(\dfrac{3}{4}\) . \(\dfrac{-1}{6}\)

= \(\dfrac{1}{8}\) 

13;   -2\(\dfrac{1}{5}\) + \(\dfrac{5}{6}\): \(\dfrac{10}{9}\) - \(\dfrac{-1}{12}\)

   =   -\(\dfrac{11}{5}\) + \(\dfrac{3}{4}\) + \(\dfrac{1}{12}\)

  = - \(\dfrac{29}{20}\) + \(\dfrac{1}{12}\)

= - \(\dfrac{41}{30}\)

Answer 6

14; \(\dfrac{-5}{9}\). \(\dfrac{13}{28}\)  - \(\dfrac{13}{28}\).\(\dfrac{4}{9}\)

 =- \(\dfrac{13}{28}\).(\(\dfrac{5}{9}\) + \(\dfrac{4}{9}\))

= - \(\dfrac{13}{28}\)

Answer 7

15; \(\dfrac{1}{2}\).\(\dfrac{-4}{5}\) + \(\dfrac{3}{2}\).\(\dfrac{-4}{5}\)

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

= - \(\dfrac{4}{5}\).2

= - \(\dfrac{8}{5}\)

Answer 8

16;   (\(\dfrac{2}{11}\) - \(\dfrac{3}{5}\)) : \(\dfrac{4}{5}\) + \(\dfrac{-1}{2}\) 

    = - \(\dfrac{23}{55}\) : \(\dfrac{4}{5}\) - \(\dfrac{1}{2}\)

   = - \(\dfrac{23}{44}\) - \(\dfrac{1}{2}\)

= - \(\dfrac{45}{44}\)

Answer 9

17; \(\dfrac{9}{31}\) .\(\dfrac{15}{17}\) + \(\dfrac{9}{31}\).\(\dfrac{16}{17}\)

=   \(\dfrac{9}{31}\).(\(\dfrac{15}{17}\) + \(\dfrac{16}{17}\))

= \(\dfrac{9}{31}\).\(\dfrac{31}{17}\)

= \(\dfrac{9}{17}\)

Answer 10

18;  \(\dfrac{15}{17}\).\(\dfrac{21}{19}\) - \(\dfrac{15}{17}\).\(\dfrac{10}{19}\) + \(\dfrac{15}{17}\).\(\dfrac{8}{19}\)

    = \(\dfrac{15}{17}\).(\(\dfrac{21}{19}\) - \(\dfrac{10}{19}\) + \(\dfrac{8}{19}\))

   = \(\dfrac{15}{17}\). \(\dfrac{19}{19}\)

= \(\dfrac{15}{17}\)

Answer 11

19; \(\dfrac{8}{11}\).\(\dfrac{5}{17}\) - \(\dfrac{8}{11}\).\(\dfrac{22}{17}\) + \(\dfrac{7}{11}\)

    = \(\dfrac{8}{11}\).(\(\dfrac{5}{17}\) - \(\dfrac{22}{17}\)) + \(\dfrac{7}{11}\)
   =  \(\dfrac{8}{11}\).(-\(\dfrac{17}{17}\)) + \(\dfrac{7}{11}\)

= - \(\dfrac{8}{11}\) + \(\dfrac{7}{11}\)

 = - \(\dfrac{1}{11}\)

Answer 12

20; \(\dfrac{2}{5}\).\(\dfrac{7}{11}\) + \(\dfrac{2}{5}\).\(\dfrac{4}{11}\)

=     \(\dfrac{2}{5}\).(\(\dfrac{7}{11}\) + \(\dfrac{4}{11}\))

 = \(\dfrac{2}{5}\)

Answer 13

21; \(\dfrac{7}{19}\).\(\dfrac{1}{3}\) + \(\dfrac{7}{19}\).\(\dfrac{2}{13}\) + \(\dfrac{12}{19}\)

  = \(\dfrac{7}{19}\).(\(\dfrac{1}{3}\) + \(\dfrac{2}{13}\)) + \(\dfrac{12}{19}\)

= \(\dfrac{7}{19}\).\(\dfrac{19}{39}\) + \(\dfrac{12}{19}\)

=   \(\dfrac{601}{741}\)