Ta có : \(\frac{\frac{3}{5}+\frac{3}{7}-\frac{1}{3}+\frac{3}{11}}{\frac{6}{5}+\frac{6}{7}-\frac{2}{3}+\frac{6}{11}}=\frac{\frac{3}{5}+\frac{3}{7}-\frac{1}{3}+\frac{3}{11}}{2\left(\frac{3}{5}+\frac{3}{7}-\frac{1}{3}+\frac{3}{11}\right)}=\frac{1}{2}\)

Lại có : \(\frac{\left(\frac{1}{4}-\frac{1}{5}-\frac{1}{20}\right).2021}{\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{99.100}}=\frac{0.2021}{\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{99.100}}=0\)

Khi đó \(B=\frac{1}{2}+0=\frac{1}{2}\)

a) \(ĐKXĐ:\hept{\begin{cases}x\ne0;x\ne2\\x\ne-1\end{cases}}\)

\(Q=1+\left(\frac{x+1}{x^3+1}-\frac{1}{x-x^2-1}-\frac{2}{x+1}\right):\frac{x^3-2x^2}{x^3-x^2+x}\)

\(\Leftrightarrow Q=1+\left(\frac{x+1}{x^3+1}+\frac{1}{x^2-x+1}-\frac{2}{x+1}\right):\frac{x^2\left(x-2\right)}{x\left(x^2-x+1\right)}\)

\(\Leftrightarrow Q=1+\frac{\left(x+1\right)+\left(x+1\right)-2\left(x^2-x+1\right)}{\left(x+1\right)\left(x^2-x+1\right)}:\frac{x\left(x-2\right)}{x^2-x+1}\)

\(\Leftrightarrow Q=1+\frac{x+1+x+1-2x^2+2x-2}{\left(x+1\right)\left(x^2-x+1\right)}.\frac{x^2-x+1}{x\left(x-2\right)}\)

\(\Leftrightarrow Q=1+\frac{-2x^2+4x}{x\left(x+1\right)\left(x-2\right)}\)

\(\Leftrightarrow Q=1+\frac{-2x\left(x-2\right)}{x\left(x+1\right)\left(x-2\right)}\)

\(\Leftrightarrow Q=1+\frac{-2}{x+1}\)

\(\Leftrightarrow Q=\frac{x-1}{x+1}\)

b) \(\left|x-\frac{3}{4}\right|=\frac{5}{4}\)

\(\Leftrightarrow\orbr{\begin{cases}x-\frac{3}{4}=\frac{5}{4}\\x-\frac{3}{4}=-\frac{5}{4}\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x=2\left(ktm\right)\\x=-\frac{1}{2}\left(tm\right)\end{cases}}\)

Thay \(x=-\frac{1}{2}\)vào Q, ta được :

\(Q=\frac{-\frac{1}{2}-1}{-\frac{1}{2}+1}\)

\(\Leftrightarrow Q=\frac{-\frac{3}{2}}{\frac{1}{2}}\)

\(\Leftrightarrow Q=-3\)

c) Để \(Q\inℤ\)

\(\Leftrightarrow x-1⋮x+1\)

\(\Leftrightarrow x+1-2⋮x+1\)

\(\Leftrightarrow2⋮x+1\)

\(\Leftrightarrow x+1\inƯ\left(2\right)=\left\{\pm1;\pm2\right\}\)

\(\Leftrightarrow x\in\left\{-2;0;-3;1\right\}\)

Vậy để \(Q\inℤ\Leftrightarrow x\in\left\{-2;0;-3;1\right\}\)

ahihi câu 1 nó cho sẵn òi kìa... m bằng ba cái phân số trên đó há há há :)))

câu 3 bấm máy tính đi x=0 đó

mình cần lời giải cơ

a) \(M=\frac{211241}{849338}\)

b) a = 9; b = 11

\(\frac{7}{12}x+0,75=-2\frac{1}{6}=-\frac{13}{6}\)

\(=>\frac{7}{12}x=-\frac{13}{6}-0,75=-\frac{13}{6}-\frac{3}{4}=-\frac{35}{12}\)

\(=>x=-\frac{35}{12}:\frac{7}{12}=-\frac{35}{12}.\frac{12}{7}=-\frac{35}{7}=-5\)

Vậy x=-5

\(-1<\frac{x}{4}<\frac{1}{2}\)

\(<=>-\frac{4}{4}<\frac{x}{4}<\frac{2}{4}\)

<=>-4<x<2

<=>x E {-3;-2;-1;0;1}

Vậy.......................