a) A=\(\left(\frac{-5}{11}\right).\frac{7}{15}.\left(\frac{11}{-5}\right).\left(-30\right)\)

b) B=\(\left(-\frac{1}{6}\right).\left(\frac{-15}{19}\right).\left(\frac{38}{45}\right)\)

c) C= \(\left(\frac{-5}{9}\right).\frac{3}{11}+\left(\frac{-13}{18}\right).\frac{3}{11}\)

d) D= \(\left(2\frac{2}{15}.\frac{9}{17}.\frac{3}{32}\right):\left(\frac{-3}{27}\right)\)

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. \(\left(1-\frac{1}{2}\right).\left(1-\frac{1}{3}\right).\left(1-\frac{1}{4}\right)....\left(1-\frac{1}{n+1}\right)n\in Z\)

Bỏ ngoặc rồi tính :

a, \(\frac{6}{7}\) + \(\left(\frac{2}{11}-\frac{6}{7}\right)\)- \(\left(\frac{13}{11}+1\right)\)

b, \(\frac{-5}{11}\)- \(\left(\frac{17}{19}-\frac{5}{11}\right)\)- \(\left(\frac{17}{19}-2\right)\)

c, \(-\left(\frac{11}{14}-\frac{8}{9}\right)\)+ \(\left(\frac{-3}{14}-\frac{8}{19}\right)\)

d, \(\frac{3}{2}\) - \(\left[\left(\frac{-4}{7}\right)-\left(\frac{1}{2}+\frac{5}{8}\right)\right]\)

tìm x,biết:

a)\(\frac{2}{\left(x+2\right)\left(x+4\right)}+\frac{4}{\left(x+4\right)\left(x+8\right)}+\frac{6}{\left(x+8\right)\left(x+14\right)}=\frac{x}{\left(x+2\right)\left(x+14\right)}\)

b)\(\frac{x+1}{10}+\frac{x+1}{11}+\frac{x+1}{12}=\frac{x+1}{13}+\frac{x+1}{14}\)

c)\(\left(x+2\right)^2=\frac{38}{25}+\frac{9}{10}-\frac{11}{15}+\frac{13}{21}-\frac{15}{28}+\frac{17}{36}-...+\frac{197}{4851}-\frac{199}{4950}\)

giúp tớ với,huhu

1.Tìm x :

a,\(\frac{1}{5.6}+\frac{1}{6.7}+...+\frac{1}{x\left(x+1\right)}=\frac{13}{90}\)

b,\(\frac{1}{1.4}+\frac{1}{4.7}+\frac{1}{7.10}+...+\frac{1}{x\left(x+3\right)}=\frac{49}{148}\)

c,\(\frac{7}{\left(x+3\right)\left(x+10\right)}+\frac{11}{\left(x+10\right)\left(x+21\right)}\)\(+\frac{1}{\left(x+21\right)\left(x+34\right)}=\frac{x}{\left(x+3\right)\left(x+34\right)}\)

d,\(\frac{3}{\left(x-4\right)\left(x-7\right)}+\frac{6}{\left(x-7\right)\left(x-13\right)}\)\(+\frac{15}{\left(x-13\right)\left(x-28\right)}\)\(-\frac{1}{x-38}=\frac{-1}{20}\)

a, \(\frac{4}{9.13}+\frac{11}{13.24}+\frac{7}{38.45}\)

b, \(\left(\frac{-3}{8}+\frac{5}{9}:\frac{-11}{37}\right).\left(\frac{33}{19}-\frac{7}{22}.\frac{47}{17}\right).\left(2-\frac{7}{13}.\frac{7}{26}\right)\)

c, \(3.\left|2-1\frac{1}{14}\right|-\left|3\left(\frac{-3}{7}\right)\right|-2\left(4,025-2,885\right)\)

d,\(\left(\frac{1}{4}-1\right)\left(\frac{1}{5}-1\right).....\left(\frac{1}{2000}-1\right)\left(\frac{1}{2001}-1\right)\)