Tìm x, biết :

a, \(\left(\frac{1}{1\cdot2\cdot3}+\frac{1}{2\cdot3\cdot4}+...+\frac{1}{98\cdot99\cdot100}\right)x=-3\);

b, \(\left(\frac{\frac{2000}{1}+\frac{1999}{2}+...+\frac{1}{2000}}{\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2001}}\right)x=\frac{-1}{5}\).

c,\(\left(\frac{\frac{2000}{1}+\frac{1999}{2}+...+\frac{1}{2000}+2000}{1+\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2001}}\right):x=\frac{-2001}{2002}\).

TÍNH HỢP LÍ

a)\(\frac{\frac{4}{17}-\frac{4}{49}-\frac{4}{131}}{\frac{-3}{17}+\frac{3}{49}+\frac{3}{131}}\)

b)\(\frac{-1}{2}+\frac{3}{5}+\frac{-1}{9}+\frac{1}{27}+\frac{7}{18}+\frac{4}{35}+\frac{2}{7}\)

c)\(\frac{3.8.15....9999}{4.9.16.....10000}\)

d)\(\frac{\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{2000}}{\frac{1999}{1}+\frac{1998}{2}+\frac{1997}{3}+...+\frac{1}{1999}}\)

câu 1:thực hiện phép tính (tính nhanh nếu có thể): 

a, \(\frac{-7}{25}.\frac{11}{13}+\frac{-7}{25}.\frac{2}{13}-\frac{18}{25}\)

b,\(\frac{5}{7}.\frac{1}{3}-\frac{5}{7}.\frac{1}{4}-\frac{5}{7}.\frac{1}{12}\)

c,\(5\frac{2}{5}.4\frac{2}{7}+5\frac{5}{7}.5\frac{2}{5}\)

d,\(75\%-1\frac{1}{2}+0,5:\frac{5}{12}-\left(\frac{-1}{2}\right)^2\)

câu 2:tìm x biết:

a, \(x+\frac{1}{6}=\frac{-3}{8}\)

b, \(\frac{1}{2}x+\frac{1}{8}x=\frac{3}{4}\)

c,\(2-\left|\frac{3}{4}-x\right|=\frac{7}{12}\)

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

GIÚP MIK VS MAI MIK PHẢI NỘP BÀI RỒI!

1)Cho A=\(\frac{196}{197}\)+\(\frac{197}{198}\)

B=\(\frac{196+197}{197+198}\)

So sánh A và B

2)Cho B=\(\frac{1}{4}\)+\(\frac{1}{5}+\frac{1}{6}+\frac{1}{7}+...+\frac{1}{19}\).Chứng minh B>1

3)Tính nhanh

\(\frac{\frac{3}{5}+\frac{3}{7}-\frac{3}{11}}{\frac{4}{5}+\frac{4}{7}-\frac{4}{11}}\)