Question

Tính:

a) \(\frac{2}{7}:\frac{13}{24}+\frac{2}{7}:\frac{5}{24}\)

b)\(\frac{15}{24}-\frac{3}{8}-\frac{1}{6}\)

c)\(\frac{7}{13}.\frac{5}{14}.\frac{39}{15}\)

Answer 1

a)<=>2/7:(13/24+5/24)   b)<=>15/24-9/24-4/24       c)=7.5.39/13.14.15

<=>2/7:3/4                        <=>2/24=1/12                      =3/2.3

<=>2/7x4/3                                                                    =1/2

<=>8/21                                     

Answer 2

a. \(\frac{2}{7}:\frac{13}{24}+\frac{2}{7}:\frac{5}{24}\)

= \(\frac{2}{7}:\left(\frac{13}{24}+\frac{5}{24}\right)\)

= \(\frac{2}{7}:\frac{3}{4}\)

= \(\frac{8}{21}\)

b. \(\frac{15}{24}-\frac{3}{8}-\frac{1}{6}\)

= \(\frac{15}{24}-\frac{9}{24}-\frac{4}{24}\)

= \(\frac{2}{24}=\frac{1}{12}\)

c. \(\frac{7}{13}.\frac{5}{14}.\frac{39}{15}\)

= \(\frac{7.5.3.13}{13.2.7.3.5}\)

= \(\frac{1}{2}\)

Answer 3

\(a,\frac{2}{7}:\frac{13}{24}+\frac{2}{7}:\frac{5}{24}\)

\(=\frac{2}{7}\cdot\frac{24}{13}+\frac{2}{7}\cdot\frac{24}{5}\)

\(=\frac{2}{7}\left(\frac{24}{13}+\frac{24}{5}\right)\)

\(=\frac{2}{7}\cdot\frac{432}{65}\)

\(=\frac{864}{455}\)

\(b,\frac{15}{24}-\frac{3}{8}-\frac{1}{6}\)

\(=\frac{1}{4}-\frac{1}{6}\)

\(=\frac{1}{12}\)

\(c,\frac{7}{13}\cdot\frac{5}{24}\cdot\frac{39}{15}\)

\(=\frac{7\cdot5\cdot39}{13\cdot24\cdot15}\)

\(=\frac{7}{24}\)