\(\dfrac{1}{3}+\dfrac{2}{3}\times\dfrac{1}{x}=-7\)

\(\dfrac{1}{3}\times\dfrac{1}{x}=-7-\dfrac{1}{3}\)

\(\dfrac{1}{3}\times\dfrac{1}{x}=-\dfrac{22}{3}\)

\(\dfrac{1}{x}=\dfrac{2}{3}:-\dfrac{22}{3}\)

\(x=-\dfrac{1}{11}\)

\(\dfrac{13}{4}+\dfrac{17}{40}\times100+\dfrac{27}{4}+47+\dfrac{1}{2}=\dfrac{130}{40}+\dfrac{17}{40}\times\dfrac{4000}{40}+\dfrac{270}{40}+\dfrac{1180}{40}+\dfrac{20}{40}=\dfrac{4000}{40}=100\)

sao ko ghi luôn đi

đó là do ko dùng telex chứ đâu phải do tui

\(\dfrac{3x+4}{7}\le\dfrac{5x-19}{14}\)

\(\Leftrightarrow\dfrac{6x+8}{14}\le\dfrac{5x-19}{14}\)

\(\Leftrightarrow6x+8\le5x-19\)

\(\Leftrightarrow6x-5x\le-19-8\)

\(\Leftrightarrow x\le-27\)

tháng 1; 3; 5; 7; 8; 10; 12

\(\dfrac{5}{4};\dfrac{48}{60};\dfrac{36}{45};\dfrac{18}{15}\)

\(\dfrac{50}{100}x+\dfrac{1}{2}x=\dfrac{1}{2}x+\dfrac{1}{2}x=x\)