\(1,4x\frac{15}{49}-\left(\frac{4}{5}+\frac{2}{3}\right):2\frac{1}{5}\)

\(=\frac{3}{7}-\frac{22}{15}:2\frac{1}{5}\)

\(=\frac{3}{7}-\frac{2}{3}=-\frac{5}{21}\)

học tốt ~~~

\(1,4\times\frac{15}{49}-\left(\frac{4}{5}+\frac{2}{3}\right)\div2\frac{1}{5}\)

\(=\frac{14}{10}\times\frac{15}{49}-\frac{22}{15}\div\frac{11}{5}\)

\(=\frac{7}{5}\times\frac{15}{49}-\frac{22\times5}{15\times11}\)

\(=\frac{7\times15}{5\times49}-\frac{22\times5}{15\times11}\)

\(=\frac{7\times7\times3\times5}{5\times7\times7}-\frac{11\times2\times5}{3\times5\times11}\)

\(=3-\frac{2}{3}\)

\(=\frac{7}{3}\)

Giải:

B=1,4 .15/49 - (4/5+2/3) :2 1/5

B=7/5.15/49 - 22/15 : 11/5

B=3/7 - 2/3

B=-5/21

Chúc bạn học tốt!

=1,4 x\(\dfrac{15}{49}-\) \(\left(\dfrac{4}{5}+\dfrac{2}{3}\right)\) : 2\(\dfrac{1}{5}\)

=  \(\dfrac{3}{7}\) - \(\dfrac{22}{15}\) : \(\dfrac{11}{5}\)

= \(\dfrac{3}{7}\) -  \(\dfrac{2}{3}\)

= \(-\dfrac{5}{21}\) 

( 2\(\dfrac{1}{5}\) + \(\dfrac{3}{5}\) \(\times\) \(x\)) = \(\dfrac{3}{4}\)

  \(\dfrac{11}{5}\) + \(\dfrac{3}{5}\)\(x\) = \(\dfrac{3}{4}\)

            \(\dfrac{3}{5}\)\(x\) = \(\dfrac{3}{4}\) - \(\dfrac{11}{5}\)

           \(\dfrac{3}{5}\)\(x\) = - \(\dfrac{29}{20}\)

             \(x\) = -\(\dfrac{29}{12}\)

3\(\dfrac{1}{3}\) x \(x+16\)\(\dfrac{3}{4}\)= 13,25

\(\dfrac{10}{3}\) x \(x\) + \(\dfrac{67}{4}\) = 13,25

\(\dfrac{10}{3}\) x \(x\) = 13,25 - \(\dfrac{67}{4}\)

\(\dfrac{10}{3}\times x=\) \(\dfrac{103}{28}\) 

          \(x\) = \(\dfrac{103}{28}:\dfrac{10}{3}\)

          \(x=\) \(\dfrac{309}{280}\)

a: \(=\dfrac{7}{5}\cdot\dfrac{15}{49}-\dfrac{12+10}{15}:\dfrac{11}{5}\)

\(=\dfrac{3}{7}-\dfrac{22}{15}\cdot\dfrac{5}{11}=\dfrac{3}{7}-\dfrac{2}{3}=\dfrac{9-14}{21}=\dfrac{-5}{21}\)

b: =>2,8x-32=-60

=>2,8x=-28

hay x=-10

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