\(A=\frac{-2}{4}+\frac{2}{7}-\frac{5}{28}\)

\(A=\frac{-14}{28}+\frac{8}{28}-\frac{5}{28}\)

\(A=\frac{-6}{28}-\frac{5}{28}\)

\(A=\frac{-11}{28}\)

5 : 3 và 1/2 là sao ????

giải thích rõ ra thì mình sẽ giải bài B 

bạn ơi đó là dấu chia  5 chia cho 3 và 1/2

ý của bạn là \(\frac{5\div3}{\frac{1}{2}}=\frac{10}{3}\)đúng ko

A=4/63

bấm máy tính đi nha!

chúc học tốt

B = ( \(\dfrac{5}{7}.0,6:3\dfrac{1}{2}\)) . ( 40% - 1,4) . \(\left(-2\right)^3\)

= (\(\dfrac{5}{7}.\dfrac{3}{5}\): \(\dfrac{7}{2}\)) . ( \(\dfrac{2}{5}-\dfrac{7}{5}\)) . (-8)

= (\(\dfrac{15}{35}:\dfrac{7}{2}\)) . \(\dfrac{-5}{5}\) . ( -8)

= (\(\dfrac{3}{7}.\dfrac{2}{7}\)) . (-1) . (-8)

= \(\dfrac{6}{49}\) . (-1) . (-8)

= \(\dfrac{-6}{49}\) . (-8)

= \(\dfrac{48}{49}\)

Vậy: B =\(\dfrac{48}{49}\)

Nhớ tick nha

B=(\(\dfrac{3}{7}.\dfrac{2}{7}\)).(\(\dfrac{4}{10}-\dfrac{14}{10}\)).(-8)

B=\(\dfrac{3}{7}.\left(-1\right)\left(-8\right)\)

B=\(\dfrac{24}{7}\)

A= \(\frac{19}{24}\) - \(\frac{5}{9}\) 

A= \(\frac{17}{72}\)

B= 5. (-4) -4.(-5) - 20

B= -20 - (-20) - 20

B= 0 - 20

B= -20

câu c làm sao vậy bạn 

a,

\(B=\left(\dfrac{5}{7}\cdot0,6-5:\dfrac{7}{2}\right)\cdot\left(40\%-1,4\right)\cdot\left(-2\right)^3\\ =\left(\dfrac{5}{7}\cdot\dfrac{3}{5}-5\cdot\dfrac{2}{7}\right)\cdot\left(\dfrac{2}{5}-\dfrac{7}{5}\right)\cdot\left(-8\right)\\ =\left(\dfrac{3}{7}-\dfrac{10}{7}\right)\cdot\left(-1\right)\cdot\left(-8\right)\\ =\left(-1\right)\cdot\left(-1\right)\cdot\left(-8\right)\\ =\left(-8\right)\)

b,

\(\dfrac{1}{2}\cdot x+\dfrac{3}{5}\cdot\left(x-2\right)=3\\ \dfrac{1}{2}x+\dfrac{3}{5}x-\dfrac{6}{5}=3\\ x\left(\dfrac{1}{2}+\dfrac{3}{5}\right)=3+\dfrac{6}{5}\\ x\cdot\dfrac{11}{10}=\dfrac{21}{5}\\ x=\dfrac{21}{5}:\dfrac{11}{10}\\ x=\dfrac{42}{11}\\ Vậy......\)