Câu hỏi:

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Thực hiện phép tính (tính hợp lí nếu có thể):

    a) 1,56+8,44:4,221,56 + 8,44:4,22;                               b) 58+78\frac{5}{{ - 8}} + \frac{7}{8};

    c) 1,25:1520+(25% 56):4231,25:\frac{{15}}{{20}} + \left( {25\%  - \frac{5}{6}} \right):4\frac{2}{3};                                     d) 49.726+4526.49+13\frac{4}{9}.\frac{{ - 7}}{{26}} + \frac{{45}}{{ - 26}}.\frac{4}{9} + \frac{1}{3}.

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Lời giải

Hướng dẫn giải:

a) 1,56+8,44:4,221,56 + 8,44:4,22

=1,56+2 = 1,56 + 2

=3,56 = 3,56.

c) 1,25:1520+(25% 56):4231,25:\frac{{15}}{{20}} + \left( {25\%  - \frac{5}{6}} \right):4\frac{2}{3}

=125100:34+(2510056):143 = \frac{{125}}{{100}}:\frac{3}{4} + \left( {\frac{{25}}{{100}} - \frac{5}{6}} \right):\frac{{14}}{3}

=65.43+(1456).314 = \frac{6}{5}.\frac{4}{3} + \left( {\frac{1}{4} - \frac{5}{6}} \right).\frac{3}{{14}}

=85+(3121012).314 = \frac{8}{5} + \left( {\frac{3}{{12}} - \frac{{10}}{{12}}} \right).\frac{3}{{14}}

=85+712.314 = \frac{8}{5} + \frac{{ - 7}}{{12}}.\frac{3}{{14}}

=85+18 = \frac{8}{5} + \frac{{ - 1}}{8}

=6440540=5940 = \frac{{64}}{{40}} - \frac{5}{{40}} = \frac{{59}}{{40}}.

b) 58+78\frac{5}{{ - 8}} + \frac{7}{8}

=58+78 = \frac{{ - 5}}{8} + \frac{7}{8}=28 = \frac{2}{8}.

d) 49.726+4526.49+13\frac{4}{9}.\frac{{ - 7}}{{26}} + \frac{{45}}{{ - 26}}.\frac{4}{9} + \frac{1}{3}

=49.7264526.49+13 = \frac{4}{9}.\frac{{ - 7}}{{26}} - \frac{{45}}{{26}}.\frac{4}{9} + \frac{1}{3}

=49.(7264526)+13 = \frac{4}{9}.\left( {\frac{{ - 7}}{{26}} - \frac{{45}}{{26}}} \right) + \frac{1}{3}

=49.5226+13 = \frac{4}{9}.\frac{{ - 52}}{{26}} + \frac{1}{3}

=49.(2)+13 = \frac{4}{9}.\left( { - 2} \right) + \frac{1}{3}

=89+39=59 = \frac{{ - 8}}{9} + \frac{3}{9} = \frac{{ - 5}}{9}.

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