Ta có: \(B=\dfrac{11}{13}\cdot\dfrac{40}{13}+\dfrac{37}{5}:\dfrac{7}{33}-\left(\dfrac{11}{13}+\dfrac{33}{7}:\dfrac{5}{2}\right)\)

\(=\dfrac{440}{169}+\dfrac{37}{5}\cdot\dfrac{33}{7}-\dfrac{11}{13}-\dfrac{33}{7}\cdot\dfrac{2}{5}\)

\(=\dfrac{297}{169}+\dfrac{33}{7}\cdot\left(\dfrac{37}{5}-\dfrac{2}{5}\right)\)

\(=\dfrac{297}{169}+\dfrac{33}{7}\cdot7\)

\(=\dfrac{297}{169}+33=\dfrac{5874}{169}\)

B=4*13/9*3-4/3*40/9

B=4/3*13/9-4/3*40/9

B=4/3*(13/9-40/9)

B=4/3*(-27)/9

B=4*(-3)/9

B=-4

A=6/7 + 1/7.(2/7+5/7)

A=6/7 + 1/7.7/7=6/7+1/7.1

A=6/7+1/7=7/7=1

M=8/3*2/5*3/8*10*19/2

M=(8/3*3/8)*(2/5*10)*19/2

M=1*4*19/2

M=28

c) \(\left|x\right|=3,5\Rightarrow\left[{}\begin{matrix}x=3,5\\x=-3,5\end{matrix}\right.\)

d) \(\left|x\right|=-2,7\Rightarrow x\in\varnothing\) 

l) \(\left|x+\dfrac{3}{4}\right|-5=-2\Rightarrow\left|x+\dfrac{3}{4}\right|=3\)

\(\Rightarrow\left[{}\begin{matrix}x+\dfrac{3}{4}=3\\x+\dfrac{3}{4}=-3\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=3-\dfrac{3}{4}\\x=-3-\dfrac{3}{4}\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{9}{4}\\x=\dfrac{15}{4}\end{matrix}\right.\)

Đính chính câu l \(x=-\dfrac{15}{4}\) không phải \(x=\dfrac{15}{4}\)

c) x = 3,5 hoặc -3,5

d) x = -2,7

e) x = -1,27

f) x = 0

g) x = -2

h) x = 0

l) x = 9/4

   x = -15/4

lấy máy tính cầm tay mà bấm 

\(a,\dfrac{1}{12}\times\dfrac{4}{5}=\dfrac{1\times4}{12\times5}=\dfrac{1}{15}\)

\(b,\dfrac{40}{7}\times\dfrac{21}{5}=\dfrac{40\times21}{7\times5}=\dfrac{24}{1}=24\)

\(c,\dfrac{9}{5}\div\dfrac{4}{7}=\dfrac{9}{5}\times\dfrac{7}{4}=\dfrac{9\times7}{5\times4}=\dfrac{63}{20}\)

\(d,\dfrac{11}{24}\div\dfrac{44}{3}=\dfrac{11}{24}\times\dfrac{3}{44}=\dfrac{11\times3}{24\times44}=\dfrac{1}{32}\)

con cặk

b: \(B=\dfrac{5}{2}-\dfrac{7}{2}+\dfrac{3}{8}+\dfrac{6}{8}+\dfrac{-6}{11}-\dfrac{5}{11}=-2-1+\dfrac{9}{8}=\dfrac{9}{8}-3=-\dfrac{15}{8}\)

c: \(C=\left(\dfrac{4}{3}+\dfrac{7}{3}+\dfrac{1}{3}\right)+\left(\dfrac{2}{5}+\dfrac{3}{5}\right)=4+1=5\)

d: \(D=\dfrac{4}{19}\left(\dfrac{-5}{6}-\dfrac{7}{12}\right)-\dfrac{40}{57}\)

\(=\dfrac{4}{19}\cdot\dfrac{-17}{12}-\dfrac{40}{57}=-1\)

e: \(E=\dfrac{1}{3}\left(\dfrac{4}{5}-\dfrac{9}{5}\right)+\dfrac{2}{3}=\dfrac{2}{3}-\dfrac{1}{3}=\dfrac{1}{3}\)

có câu 5 si phải là 3294 tick đúng nha