a; -\(\dfrac{4}{9}.\dfrac{7}{15}+\dfrac{4}{-9}.\dfrac{8}{15}\)

= - \(\dfrac{4}{9}\).(\(\dfrac{7}{15}+\dfrac{8}{15}\))

= - \(\dfrac{4}{9}\).1

= - \(\dfrac{4}{9}\)

b; - \(\dfrac{5}{4}.\dfrac{16}{25}\) + \(\dfrac{-5}{4}\).\(\dfrac{9}{25}\)

= - \(\dfrac{5}{4}\).(\(\dfrac{16}{25}\) + \(\dfrac{9}{25}\))

= - \(\dfrac{5}{4}\). 1

= - \(\dfrac{5}{4}\)

c; \(-\dfrac{5}{12}.\dfrac{4}{19}\) + \(\dfrac{-7}{12}.\dfrac{4}{19}-\dfrac{40}{57}\)

= - \(\dfrac{5}{12}\).\(\dfrac{4}{19}\) - \(\dfrac{7}{12}\).\(\dfrac{4}{19}\) - \(\dfrac{4}{19}\).\(\dfrac{10}{3}\)

= - \(\dfrac{4}{19}\).(\(\dfrac{5}{12}\) + \(\dfrac{7}{12}\) + \(\dfrac{10}{3}\))

= - \(\dfrac{4}{19}\).\(\dfrac{13}{3}\)

= - \(\dfrac{52}{57}\)

\(\frac{7}{8}-\frac{7}{16}-\frac{11}{32}\)

= \(\frac{28}{32}-\frac{14}{32}-\frac{11}{32}\)

= \(\frac{28-14-11}{32}\)

= \(\frac{3}{32}\)

Đề : 7/8 - 7/16 - 11/32 = ?

Chọn MSC là 32 . Ta có phép tính : 28/32 - 14/32 - 11/32 = 3/32 

Tíc nha !

\(\frac{7}{8}-\frac{7}{16}-\frac{11}{32}=\frac{7}{16}-\frac{11}{32}=\frac{3}{32}=0,09375\)

a; \(\dfrac{3}{5}\) - \(\dfrac{-7}{10}\) - \(\dfrac{13}{-20}\)

= \(\dfrac{12}{20}\) +  \(\dfrac{14}{20}\) + \(\dfrac{13}{20}\)

= \(\dfrac{39}{20}\)

b; \(\dfrac{1}{2}\) + \(\dfrac{1}{-3}\) + \(\dfrac{1}{4}\) - \(\dfrac{-1}{6}\)

= \(\dfrac{6}{12}\) - \(\dfrac{4}{12}\) + \(\dfrac{3}{12}\) + \(\dfrac{2}{12}\)

= \(\dfrac{7}{12}\)

\(\frac{7}{13}.\frac{5}{9}+\frac{7}{19}.\frac{8}{13}-3.\frac{7}{19}=\)\(\frac{-1288}{2223}\)

Kết quả = -1288/2223

R

a; 0,2.\(\dfrac{15}{36}\) - (\(\dfrac{2}{5}\) + \(\dfrac{2}{3}\)): 1%

   = \(\dfrac{1}{12}\)  - \(\dfrac{16}{15}\): \(\dfrac{1}{100}\)

  =    \(\dfrac{1}{12}\) - \(\dfrac{320}{3}\)

= \(\dfrac{1}{12}\) - \(\dfrac{1280}{12}\)
= - \(\dfrac{1279}{12}\)

b; 75% - 1\(\dfrac{1}{2}\) + 0,5 : \(\dfrac{5}{12}\)

= 0,75 - 1,5 + 1,2

= -0,75 + 1,2

= 0,45

c; 1\(\dfrac{3}{15}.0,75-\left(\dfrac{8}{15}+0,25\right)\).\(\dfrac{24}{47}\)

= \(\dfrac{28}{15}\).0,75 - \(\dfrac{47}{60}\).\(\dfrac{24}{47}\)

= \(\dfrac{7}{5}-\dfrac{2}{5}\)

= 1

d; \(\dfrac{32}{15}\): (-1\(\dfrac{1}{5}\) + 1\(\dfrac{1}{3}\))

= \(\dfrac{32}{15}\): (-\(\dfrac{6}{5}\) + \(\dfrac{4}{3}\))

= \(\dfrac{32}{15}\): \(\dfrac{2}{15}\)

= 16

e; 20 + 9\(\dfrac{1}{4}:2\dfrac{1}{4}\)

= 20 + \(\dfrac{37}{4}\) : \(\dfrac{9}{4}\)

= 20 + \(\dfrac{37}{9}\)

= \(\dfrac{217}{9}\)

g; \(\dfrac{3}{4}.\dfrac{16}{9}\)- \(\dfrac{7}{5}\): (-\(\dfrac{21}{20}\))

=  \(\dfrac{4}{3}\) - (-\(\dfrac{4}{3}\))

= \(\dfrac{4}{3}\) + \(\dfrac{4}{3}\)

= \(\dfrac{8}{3}\)

\(\dfrac{7}{16}-\dfrac{3}{8}=\dfrac{7}{16}-\dfrac{6}{16}=\dfrac{1}{16}\)

1/16

Bằng 1 phần 16 nha

\(\frac{4}{5}\cdot\frac{3}{7}+\frac{4}{5}\cdot\frac{6}{7}-\frac{4}{5}\cdot\frac{4}{14}\)

\(=\frac{4}{5}\cdot\left(\frac{3}{7}+\frac{6}{7}-\frac{4}{14}\right)\)

\(=\frac{4}{5}\cdot1=\frac{4}{5}\)

                                                                     #Louis

\(3\frac{1}{2}+4\frac{5}{7}-5\frac{5}{14}=\frac{7}{2}+\frac{33}{7}-\frac{75}{14}=\frac{49}{14}+\frac{66}{14}-\frac{75}{14}=\frac{40}{14}=\frac{20}{7}\)

#Fox

=20/7

Bạn chỉ giúp mk cách làm được ko ạ

20/7 nha

31/2+45/7-55/14  ?

\(\dfrac{20}{7}\)

    31/2+45/7-55/14 
= 217/14+90/14-55/14
= 252/14
^{_{Rồi tự rút gọn(Nếu được)}}