b, B = 1 + 2 + 2^2 + 2^3 +.....+ 2^2013
2B = 2.(1 + 2 + 2^2 + 2^3 +.....+ 2^2013)
2B = 2 + 2^2 + 2^3 + 2^4 +.....+ 2^2014
2B - B = 2^2014 - 1
B = 2^2014 - 1
bài 1: TÍNH HỢP LÝ
a, \(49\dfrac{8}{23}-\left(5\dfrac{7}{32}+14\dfrac{8}{23}\right)\)
b, \(-\dfrac{3}{7}.\dfrac{5}{9}+\dfrac{4}{9}.\dfrac{-3}{7}+2\dfrac{3}{7}\)
c, \(0,7.2\dfrac{2}{3}.20.0.375.\dfrac{5}{28}\)
d, \(\left(9\dfrac{30303}{80808}+7\dfrac{303030}{484848}\right)+4.03\)
BT1: Tính nhanh
1) \(\left(\dfrac{-4}{9}+\dfrac{3}{7}\right):1\dfrac{1}{15}+\left(\dfrac{4}{7}-\dfrac{5}{9}\right):1\dfrac{1}{15}\)
2) \(3\dfrac{2}{9}.15\dfrac{4}{7}-3\dfrac{2}{9}.8\dfrac{1}{7}+3\dfrac{2}{9}.\dfrac{15}{7}-3\dfrac{2}{9}.\dfrac{1}{7}\)
tính giá trị biểu thức
A=\(15.\left(\dfrac{3}{5}-\dfrac{2}{3}\right)+1\)
B=\(1-\dfrac{13}{9}:\dfrac{8}{19}+\dfrac{-11}{9}:\dfrac{8}{9}\)
C=\(\dfrac{6}{7}+\dfrac{5}{8}:5-\dfrac{3}{16}.\left(-2^2\right)\)
1.Tính
a) (\(\dfrac{-2}{3}\)+1\(\dfrac{1}{4}\)-\(\dfrac{1}{6}\)).\(\dfrac{-24}{10}\)
b) \(\dfrac{13}{15}\).0,25.3+(\(\dfrac{8}{15}\)-\(1\dfrac{19}{60}\)):\(1\dfrac{23}{24}\)
c) (\(\dfrac{12}{32}\)+\(\dfrac{5}{-20}\)-\(\dfrac{10}{24}\)):\(\dfrac{2}{3}\)
d) \(4\dfrac{1}{2}\):(2,5-\(3\dfrac{3}{4}\))+(\(\dfrac{-1}{2}\))\(^2\)
e) \(\dfrac{-5}{2}\):(\(\dfrac{3}{4}\)-\(\dfrac{1}{2}\))
2. Tính nhanh
a) \(\dfrac{5}{23}\).\(\dfrac{17}{26}\)+\(\dfrac{5}{23}\).\(\dfrac{10}{26}\)-\(\dfrac{5}{23}\)
b) \(\dfrac{1}{7}\).\(\dfrac{5}{9}\)+\(\dfrac{5}{9}\).\(\dfrac{2}{7}\)+\(\dfrac{5}{9}\).\(\dfrac{1}{7}\)+\(\dfrac{5}{9}\).\(\dfrac{3}{7}\)
Tính:
\(\dfrac{\dfrac{1}{3}-\dfrac{1}{5}-\dfrac{1}{7}}{\dfrac{2}{3}-\dfrac{2}{5}-\dfrac{2}{7}}\) + \(\dfrac{\dfrac{4}{7}-\dfrac{4}{9}+\dfrac{4}{11}}{\dfrac{3}{7}-\dfrac{1}{3}+\dfrac{9}{11}}\)=?
a) A= 11 \(\dfrac{3}{13}\)- ( 3\(\dfrac{4}{7}\)+ 6\(\dfrac{3}{13}\) )
b) B= ( 7\(\dfrac{4}{9}\) + 3\(\dfrac{8}{13}\) ) \(-5\dfrac{4}{9}\)
c) C= \(\dfrac{-2}{7}.\dfrac{5}{11}+\dfrac{-2}{7}.\dfrac{6}{11}+5\dfrac{4}{7}\)
d) D= \(0,7.1\dfrac{3}{5}.30.0,375.\dfrac{4}{7}\)
\(B=\left(7\dfrac{4}{9}+3\dfrac{8}{13}\right)-5\dfrac{4}{9}\)
\(C=\dfrac{-2}{7}.\dfrac{5}{11}+\dfrac{-2}{7}.\dfrac{6}{11}+5\dfrac{4}{7}\)
\(D=0,7.1\dfrac{3}{5}.30.0,375.\dfrac{4}{7}\)
Bài 2 Tính nhanh
a) \(\dfrac{5}{23}\) x \(\dfrac{17}{26}\) + \(\dfrac{5}{23}\) x \(\dfrac{10}{26}\) - \(\dfrac{5}{23}\)
b) \(\dfrac{1}{7}\) x \(\dfrac{5}{9}\) + \(\dfrac{5}{9}\) x \(\dfrac{2}{7}\) + \(\dfrac{5}{9}\) x \(\dfrac{1}{7}\) + \(\dfrac{5}{9}\) x \(\dfrac{3}{7}\)
1, Tính
\(-2\dfrac{1}{4}.\left(3\dfrac{5}{12}-1\dfrac{2}{9}\right)\)
\(\left(-25\%+0,75+\dfrac{7}{12}\right):\left(-2\dfrac{1}{8}\right)\)
2, Tính nhanh
\(\dfrac{4}{9}.19\dfrac{1}{3}-\dfrac{4}{9}.39\dfrac{1}{3}\) | \(19\dfrac{5}{8}:\dfrac{7}{12}-15\dfrac{1}{4}.\dfrac{12}{7}\)
\(\dfrac{-5}{7}.\dfrac{5}{11}+\dfrac{-5}{7}.\dfrac{2}{11}-\dfrac{5}{7}:\dfrac{11}{14}\) | \(\dfrac{4}{7}.\dfrac{89}{5}-\dfrac{4}{5}.\dfrac{82}{7}\)
\(\dfrac{5}{7}.\dfrac{-4}{19}+\dfrac{-15}{7}.\dfrac{5}{19}\) | \(8\dfrac{2}{7}-\left(3\dfrac{4}{9}+4\dfrac{2}{7}\right)\)
- Giải hộ với ạ, mấy anh, chị lớp 7,8 cũng được huhu :(( sáng mai nộp đề cương rồi. Làm ơn đi a
Muốn gì cũng hậu tạ :>