Bài 1:tính giá trị biểu thức sau:

\(B=\left(1-\frac{1}{21}\right).\left(1-\frac{1}{28}\right).\left(1-\frac{1}{36}\right)...\left(1-\frac{1}{1326}\right)\) 

Bài 2 tìm x biết

\(a,1\frac{1}{30}:\left(24\frac{1}{6}-24\frac{1}{5}\right)-\frac{1\frac{1}{2}-\frac{3}{4}}{4x-\frac{1}{2}}=\left(-1\frac{1}{15}\right):\left(8\frac{1}{5}-8\frac{1}{3}\right)\)

\(b,\left|3x-\frac{2}{5}\right|=\frac{1}{35}+\left|\frac{-3}{7}\right|\)

\(c,-3\frac{1}{2}-\left(2x+\frac{1}{2}\right):\left(-\frac{3}{7}\right)=0\)

\(d,\left(x-4\right).\left(x+2\right)\le0\)với x thuộc z

giúp mk với

hệ phương trình

1, \(\left\{{}\begin{matrix}\frac{1}{x+y}+\frac{1}{x-y}=\frac{5}{8}\\\frac{1}{x+y}-\frac{1}{x-y}=-\frac{3}{8}\end{matrix}\right.\)

2, \(\left\{{}\begin{matrix}\frac{4}{2x-3y}+\frac{5}{3x+y}=2\\\frac{3}{3x+y}-\frac{5}{2x-3y}=21\end{matrix}\right.\)

3, \(\left\{{}\begin{matrix}\frac{7}{x-y+2}+\frac{5}{x+y-1}=\frac{9}{2}\\\frac{3}{x-y+2}+\frac{2}{x+y-1}=4\end{matrix}\right.\)

4, \(\left\{{}\begin{matrix}\frac{3}{x}+\frac{5}{y}=-\frac{3}{2}\\\frac{5}{x}-\frac{2}{y}=\frac{8}{3}\end{matrix}\right.\)

5 , \(\left\{{}\begin{matrix}\frac{2}{x+y-1}-\frac{4}{x-y+1}=-\frac{14}{5}\\\frac{3}{x+y-1}+\frac{2}{x-y+1}=-\frac{13}{5}\end{matrix}\right.\)

6 , \(\left\{{}\frac{\frac{2x-3}{2y-5}=\frac{3x+1}{3y-4}}{2\left(x-3\right)-3\left(y+20=-16\right)}}\)

7\(\left\{{}\begin{matrix}\left(x+3\right)\left(y+5\right)=\left(x+1\right)\left(y+8\right)\\\left(2x-3\right)\left(5y+7\right)=2\left(5x-6\right)\left(y+1\right)\end{matrix}\right.\)

1.Tìm x biết

a) \(\left(\frac{2}{5}-x\right)\):\(1\frac{1}{3}+\frac{1}{2}=-4\)

b) \(\left(-3+\frac{3}{x}-\frac{1}{3}\right):\left(1+\frac{2}{5}+\frac{2}{3}\right)=-\frac{5}{4}\)

c) \(\frac{-3x}{4}.\left(\frac{1}{x}+\frac{2}{7}\right)=0\)

d) 3-\(\frac{1-\frac{1}{2}}{1+\frac{1}{x}}=2\frac{2}{3}\)

e)\(\left(2x+\frac{1}{3}\right)^2=\frac{9}{16}\)

f) \(4^x+4^{x+3}=4160\)

g) \(\left(x-2,5\right):1\frac{1}{2}=x:2\)

h) \(\left(\frac{1}{3}+x\right):\left(x+\frac{3}{4}\right)=\frac{7}{9}\)

i) 0,81:\(\frac{x}{2}=\frac{16}{x^4}:\left(-0,9\right)\)

2. Tìm x, biết:

a)\(\left(152\frac{2}{4}-148\frac{3}{8}\right):0,2=x:0,3\)

b) \(\left[\left(6\frac{3}{5}-3\frac{3}{14}\right):2,5\right]:\left(21-1,25\right)=x:5\frac{5}{6}\)

Giải phương trình:

1. \(\frac{2x+3}{4}-\frac{5x+3}{6}=\frac{3-4x}{12}\)

2. \(\frac{3.\left(2x+1\right)}{4}-1=\frac{15x-1}{10}\)

3. \(\frac{2x-1}{5}-\frac{x-2}{3}=\frac{x+7}{15}\)

4. \(\frac{x+3}{2}-\frac{x-1}{3}=\frac{x+5}{6}+1\)

5. \(\frac{x-4}{5}-\frac{3x-2}{10}-x=\frac{2x-5}{3}-\frac{7x+2}{6}\)

6. \(\frac{\left(x+2\right)\left(x+10\right)}{3}-\frac{\left(x+4\right)\left(x+10\right)}{12}=\frac{\left(x-2\right)\left(x+4\right)}{4}\)

7. \(\frac{\left(x+2\right)^2}{8}-2\left(2x-1\right)=25+\frac{\left(x-2\right)^2}{8}\)

8.\(\frac{7x^2-14x-5}{5}=\frac{\left(2x+1\right)^2}{5}-\frac{\left(x-1\right)^2}{3}\)

9. \(\frac{\left(2x-3\right)\left(2x+3\right)}{8}=\frac{\left(x-4\right)^2}{6}+\frac{\left(x-2\right)^2}{3}\)

10. \(\frac{x+1}{35}+\frac{x+3}{33}=\frac{x+5}{31}+\frac{x+7}{29}\)

Bài 1 : Tính

1) \(\frac{4}{7}-\frac{1}{14}+\left|\frac{-5}{21}\right|\)

2) \(\left|\frac{-2}{3}\right|-\frac{1}{2}+3\)

3) \(\left|\frac{7}{-4}\right|-\frac{5}{8}+\frac{-2}{3}\)

4) \(\frac{4}{5}+\left|\frac{-3}{2}\right|+\frac{1}{-4}\)

5) \(\left|\frac{-1}{4}\right|-3+\frac{3}{4}\)

6) \(\left|\frac{-1}{3}\right|-\frac{5}{4}+\frac{1}{5}\)

Bài 2 : Tìm x, biết :

1) \(x-\left|1\frac{1}{6}\right|=\frac{5}{21}\)

2) \(x+\left|-1\frac{2}{3}\right|=\left|-\frac{3}{4}\right|\)

3) \(\left|x-\frac{1}{3}\right|=\frac{5}{2}\)

4) \(\left|x+\frac{2}{3}\right|=0\)

5) \(\left|x+2\right|=\frac{1}{3}-\frac{1}{5}\)

6) \(\left|x-4\right|=\frac{1}{5}-\left(\frac{1}{2}-\frac{5}{4}\right)\)

7) \(\left|x-\frac{5}{4}\right|=-\frac{1}{3}\)

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E cần gấp lắm ạ, cảm ơn.

Bài 1 : Tính

1) \(\frac{4}{7}-\frac{1}{14}+\left|\frac{-5}{21}\right|\)

2) \(\left|\frac{-2}{3}\right|-\frac{1}{2}+3\)

3) \(\left|\frac{7}{-4}\right|-\frac{5}{8}+\frac{-2}{3}\)

4) \(\frac{4}{5}+\left|\frac{-3}{2}\right|+\frac{1}{-4}\)

5) \(\left|\frac{-1}{4}\right|-3+\frac{3}{4}\)

6) \(\left|\frac{-1}{3}\right|-\frac{5}{4}+\frac{1}{5}\)

Bài 2 : Tìm x, biết :

1) \(x-\left|1\frac{1}{6}\right|=\frac{5}{21}\)

2) \(x+\left|-1\frac{2}{3}\right|=\left|-\frac{3}{4}\right|\)

3) \(\left|x-\frac{1}{3}\right|=\frac{5}{2}\)

4) \(\left|x+\frac{2}{3}\right|=0\)

5) \(\left|x+2\right|=\frac{1}{3}-\frac{1}{5}\)

6) \(\left|x-4\right|=\frac{1}{5}-\left(\frac{1}{2}-\frac{5}{4}\right)\)

7) \(\left|x-\frac{5}{4}\right|=-\frac{1}{3}\)

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E đang cần gấp, cảm ơn :)