Bỏ dấu ngoặc rồi tính:

a)\(\left( {\frac{{ - 3}}{7}} \right) + \left( {\frac{5}{6} - \frac{4}{7}} \right);\)           

b)\(\frac{3}{5} - \left( {\frac{2}{3} + \frac{1}{5}} \right);\)

c)\(\left[ {\left( {\frac{{ - 1}}{3} + 1} \right) - \left( {\frac{2}{3} - \frac{1}{5}} \right)} \right];\)                  

d)\(1\frac{1}{3} + \left( {\frac{2}{3} - \frac{3}{4}} \right) - \left( {0,8 + 1\frac{1}{5}} \right)\).

1. \(\frac{1}{3}-\frac{3}{5}+\frac{5}{7}-\frac{7}{9}+\frac{9}{11}-\frac{11}{13}+\frac{11}{15}+\frac{11}{13}-\frac{9}{11}+\frac{7}{9}-\frac{5}{7}+\frac{3}{5}-\frac{1}{3}\)
2. \(\frac{-3}{4}.31\frac{11}{23}-0,75.8\frac{12}{28}\)
3. \(\left(2\frac{1}{3}+3\frac{1}{2}\right):\left(-4\frac{1}{6}+3\frac{1}{7}\right)+7\frac{1}{2}\)
4. \(4\frac{5}{9}:\left(-\frac{5}{7}\right)+5\frac{4}{9}:\left(-\frac{5}{7}\right)\)
5. \(\frac{2}{3}-4\left(\frac{1}{2}+\frac{3}{4}\right)\)
6. \(\left(1-\frac{1}{2}\right).\left(1-\frac{1}{3}\right).\left(1-\frac{1}{4}\right)....\left(1-\frac{1}{n+1}\right)n\in Z\)

a)\(\left(-2\frac{1}{5}\right).\left(\frac{-9}{11}\right).\left(-1\frac{1}{14}\right).\frac{2}{5}\)

b) \(1+\frac{1}{1+\frac{1}{2}}\)

c) \(\orbr{\begin{cases}5\\3\end{cases}-\left(-\frac{1}{4}\right):\left(1\frac{1}{5}\right):\left(\frac{5}{8}+\frac{9}{4}\right)}\)

lưu ý phần c từ chỗ \(\frac{5}{3}\)cho đến \(1\frac{1}{5}\)là đóng ngoặc vuông nhưng vì chỉ có thể viết một cái ngoặc vuông nên đã đánh 2 dấu ngoặc chòn.

Tính :

1 + 3 + 5 + 7 + ... + (2n - 1) = 225 

Giải :

Theo công thức tính dãy số , ta có :

\(\frac{\left\{\left[\left(2n-1\right)-1\right]:2+1\right\}.\left[\left(2n-1\right)+1\right]}{2}=225\)

\(\frac{\left\{\left[2n-2\right]:2+1\right\}.2n}{2}=225\)

\(\left\{\left[2n-2\right]:2+1\right\}.n=450\)(Lượt giản thừa số 2)

\(\left\{\frac{2n-2}{2}+1\right\}.n=225\)

\(\left\{\frac{2n-2}{2}+\frac{2}{2}\right\}.n=225\)

\(\frac{2n-2+2}{2}.n=225\)

\(\frac{2n}{2}.n=225\)

\(n^2=225\)

\(\Rightarrow n=\sqrt{225}=15\)

tim x :

\(a.\left|x+5\right|=\frac{1}{7}-\left|\frac{4}{3}-\frac{1}{6}\right|\)|

\(b.\left|x+\frac{2}{3}\right|=\frac{1}{2}-\left[\frac{1}{4}-\frac{2}{3}\right]\)đau [  ] là dấu ngoặc đơn nha!

\(c.\left|x-\frac{1}{5}\right|=\left|\frac{-5}{2}\right|-\left[\frac{1}{4}-\frac{2}{3}\right]\)đau [  ] là dấu ngoặc đơn nha!

\(d.\left|x-\frac{5}{2}\right|=\frac{4}{3}-\left[\frac{2}{3}-\frac{1}{6}\right]\)đau [  ] là dấu ngoặc đơn nha!

ai nhanh nhất mk tk !

Bài 1 Thưc hiện phép tính ( tính nhanh nếu có thể)

a)\(\frac{-1}{24}-\left[\frac{1}{4}-\left(\frac{1}{2}-\frac{7}{8}\right)\right]\)

b)\(\left(\frac{5}{7}-\frac{7}{5}\right)-\left[\frac{1}{2}-\left(\frac{-2}{7}-\frac{1}{10}\right)\right]\)

C)\(\left(\frac{-1}{2}\right)-\left(\frac{-3}{5}\right)+\left(\frac{-1}{9}\right)+\frac{1}{17}-\left(\frac{-2}{7}\right)+\frac{4}{35}-\frac{7}{18}\)

d)\(\left(3-\frac{1}{4}+\frac{2}{3}\right)-\left(5-\frac{1}{3}-\frac{6}{5}\right)-\left(6-\frac{7}{4}+\frac{3}{2}\right)\)

Giúp mik với

Tính nhanh:

a. A=\(\left(-1\right)^{2n}.\left(-1\right)^n.\left(-1\right)^{n+1}\left(n\in N\right)\)

b. B=\(\left(10000-1^2\right)\left(10000-2^2\right)\left(10000-3^2\right)..\left(10000-1000^2\right)\)

c. C=\(\left(\frac{1}{125}-\frac{1}{1^3}\right)\left(\frac{1}{125}-\frac{1}{2^3}\right)\left(\frac{1}{125}-\frac{1}{3^3}\right)...\left(\frac{1}{125}-\frac{1}{25^3}\right)\)

d. D=\(1999^{\left(1000-1^3\right)\left(1000-2^3\right)\left(1000-3^3\right)...\left(1000-10^3\right)}\)

a,\(\frac{-1}{24}-\left[\frac{1}{4}-\left(\frac{1}{2}-\frac{7}{8}\right)\right]\)

b,\(\left[\frac{5}{7}-\frac{7}{5}\right]-\left[\frac{1}{2}-\left(\frac{-2}{7}-\frac{1}{10}\right)\right]\)

c,\(\left(\frac{-1}{2}\right)-\left(\frac{-3}{5}\right)+\left(\frac{-1}{9}\right)+\frac{1}{71}-\left(\frac{-2}{7}\right)+\frac{4}{35}-\frac{7}{8}\)

d,\(\left(3-\frac{1}{4}+\frac{2}{3}\right)-\left(5-\frac{1}{3}-\frac{6}{5}\right)-\left(6-\frac{7}{4}+\frac{3}{2}\right)\)

e,\(\left(\frac{1}{2}-\frac{13}{14}\right):\frac{5}{7}-\left(\frac{-2}{21}+\frac{1}{7}\right):\frac{5}{7}\)

g,\(\frac{4}{9}:\left(\frac{-1}{7}\right)+6\frac{5}{9}:\left(\frac{-1}{7}\right)\)