Tìm x

b)\(\left(x-\dfrac{1}{2}\right):\dfrac{1}{3}+\dfrac{5}{7}=9\dfrac{5}{7}\)

c) \(\dfrac{1}{2}x-\dfrac{3}{4}=\dfrac{14}{9}.\dfrac{3}{7}\)

Tính:

B=\(\dfrac{1+2+2^2+2^3+...2^{2008}}{1-2^{2009}}\)

Tìm x, biết:

a) x+\(\dfrac{1}{6}\)=\(\dfrac{-3}{8}\)              b) \(2-\left(\dfrac{3}{4}-x\right)=\dfrac{7}{12}\)

c) \(\dfrac{1}{2}x\)+\(\dfrac{1}{8}x=\dfrac{3}{4}\)         d) 75%-\(1\dfrac{1}{2}+0,5:\dfrac{5}{12}-\left(\dfrac{-1}{2}\right)^2\)

Thực hiện phép tính (tính nhanh nếu có thể)

c) \(5\dfrac{2}{5}\)✖\(4\dfrac{2}{7}\)+\(5\dfrac{5}{7}\)✖\(5\dfrac{2}{5}\)

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

e) \(\dfrac{3}{1.4}\)+\(\dfrac{3}{4.7}\)+\(\dfrac{3}{7.10}\)+...+\(\dfrac{3}{40.43}\)

Bài 3: Tính nhanh:
a) \(15\dfrac{3}{13}\)-\(\left(3\dfrac{4}{7}+8\dfrac{3}{13}\right)\)

b) \(\left(7\dfrac{4}{9}+4\dfrac{7}{11}\right)\)-\(3\dfrac{4}{9}\)

c) \(\dfrac{-7}{9}\).\(\dfrac{4}{11}\)+\(\dfrac{-7}{9}\).\(\dfrac{7}{11}\)+\(5\dfrac{7}{9}\)

d) 50%.\(1\dfrac{1}{3}\).10.\(\dfrac{7}{35}\).0,75

e) \(\dfrac{3}{1.4}\)+\(\dfrac{3}{4.7}\)+\(\dfrac{3}{7.10}\)+...+\(\dfrac{3}{40.43}\)

e) \(\left(15-6\dfrac{13}{18}\right)\):\(12\dfrac{1}{27}\)-\(2\dfrac{1}{8}\):\(1\dfrac{11}{40}\)

g) (-3,2).\(\dfrac{-15}{64}\)+\(\left(0,8-2\dfrac{4}{15}\right)\):\(3\dfrac{2}{3}\)

b) \(\dfrac{2}{5}\)+\(\dfrac{3}{5}\):(\(\dfrac{3}{5}\)+\(\dfrac{-2}{3}\))\(-3\dfrac{1}{2}\)

c) (\(4-\dfrac{5}{12}\)):3+\(\dfrac{7}{36}\)

d) (\(2+\dfrac{5}{6}\)):\(1\dfrac{1}{5}\)+\(\dfrac{-7}{12}\)