Tính \(\dfrac{A}{B}\) biết rằng:
A = \(\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{1}{4}+...+\dfrac{1}{200}\)
B = \(\dfrac{1}{199}+\dfrac{2}{198}+\dfrac{3}{197}+...+\dfrac{198}{2}+\dfrac{199}{1}\)
Giúp mik nha! mik tick cho
Bài 1: Thực hiện phép tính
a) \(\left(\dfrac{3}{8}+\dfrac{-3}{4}+\dfrac{7}{12}\right):\dfrac{5}{6}+\dfrac{1}{2}\)
b) \(\dfrac{1}{2}+\dfrac{3}{4}-\left(\dfrac{3}{4}-\dfrac{4}{5}\right)\)
c) \(6\dfrac{5}{12}:2\dfrac{3}{4}+11\dfrac{1}{4}.\left(\dfrac{1}{3}\dfrac{1}{5}\right)\)
d)\(\left(\dfrac{7}{8}-\dfrac{3}{4}\right).1\dfrac{1}{3}-\dfrac{2}{7}.\left(3,5\right)^2\)
e)\(\left(\dfrac{3}{5}+0,415-\dfrac{3}{200}\right).2\dfrac{2}{3}.0,25\)
f)\(\dfrac{5}{16}:0,125-\left(2\dfrac{1}{4}-0,6\right).\dfrac{10}{11}\)
g) \(0,25:\left(10,3-9,8\right)-\dfrac{3}{4}\)
h)\(1\dfrac{13}{15}.0,75-\left(\dfrac{11}{20}+20\%\right):\dfrac{7}{3}\)
i)\(\dfrac{\left(\dfrac{1}{2-0,75}\right).\left(0,2-\dfrac{2}{5}\right)}{\dfrac{5}{9}-1\dfrac{1}{12}}\)
k)\(\dfrac{\dfrac{2}{3}+\dfrac{2}{7}-\dfrac{1}{14}}{-1-\dfrac{3}{7}+\dfrac{3}{28}}\)
Bài 2: Tính bằng cánh hợp lí
A=\(0,7.2\dfrac{2}{3}.20.0,375.\dfrac{5}{28}\)
B=\(\left(9\dfrac{30303}{80808}+7\dfrac{303030}{484848}\right)+4,03\)
C=\(\left(9,75.21\dfrac{3}{7}+\dfrac{39}{4}.18\dfrac{4}{7}\right).\dfrac{15}{78}\)
D=\(10101.\left(\dfrac{5}{111111}+\dfrac{5}{222222}-\dfrac{4}{3.7.11.13.37}\right)\)
tính nhanh :
a) \(6\dfrac{5}{7}-\left(1\dfrac{3}{4}+2\dfrac{5}{7}\right)\)
b) \(7\dfrac{5}{11}-\left(2\dfrac{3}{7}+3\dfrac{5}{11}\right)\)
c) \(\dfrac{1}{3}.\dfrac{4}{5}+\dfrac{1}{3}.\dfrac{6}{5}-\dfrac{4}{3}\)
d) \(\left(\dfrac{-4}{5}+\dfrac{4}{3}\right)+\left(\dfrac{-5}{4}+\dfrac{14}{5}\right)-\dfrac{7}{3}\)
e) \(\dfrac{-5}{7}.\dfrac{2}{11}+\dfrac{-5}{7}.\dfrac{9}{14}+1\dfrac{5}{7}\)
a) Tìm tập hợp số nguyên x ; y sao cho :
\(\left(1\dfrac{3}{4}-\dfrac{6}{4}\right):\left(1\dfrac{1}{5}+2\dfrac{2}{5}+20\%\right)< x< 1\dfrac{1}{5}\cdot1\dfrac{3}{4}+3\dfrac{2}{11}:2\dfrac{3}{21}\)
1. Tìm x, biết
a. \(\dfrac{1}{2}x-\dfrac{3}{4}x-\dfrac{7}{3}=\dfrac{-5}{6}\)
b. \(Ix-\dfrac{1}{6}I+\dfrac{-5}{12}=\dfrac{4}{7}.\dfrac{14}{48}\)
tính hợp lí:
a)\(\left(4\dfrac{5}{37}-3\dfrac{4}{5}+8\dfrac{15}{29}\right)-\left(3\dfrac{5}{37}-6\dfrac{14}{29}\right)\)
b) \(60\dfrac{7}{13}+50\dfrac{8}{13}-11\dfrac{2}{13}\)
c) \(\dfrac{\dfrac{2}{3}+\dfrac{2}{7}-\dfrac{1}{14}}{-1-\dfrac{3}{7}+\dfrac{3}{28}}\)
Tìm x biết:
a) \(\dfrac{x+5}{3}\)=\(\dfrac{x-6}{7}\)
b) x - \(\dfrac{20}{11.13}\)-\(\dfrac{20}{13.15}\)-\(\dfrac{20}{15.17}\)-...-\(\dfrac{20}{53.55}\)=\(\dfrac{3}{11}\)
\(\dfrac{1}{3}\)+\(\dfrac{1}{6}\)+\(\dfrac{1}{10}\)+...+\(\dfrac{2}{n\left(n+1\right)}\)=\(\dfrac{2015}{2016}\)
TÍnh A=\(\dfrac{1}{1.2}-\dfrac{1}{1.2.3}+\dfrac{1}{2.3}-\dfrac{1}{2.3.4}+\dfrac{1}{3.4}-\dfrac{1}{3.4.5}+...+\dfrac{1}{99.100}-\dfrac{1}{99.100.101}\)
B=\(\dfrac{5}{1.2.3.4}+\dfrac{5}{2.3.4.5}+...+\dfrac{5}{98.99.100.101}\)
C=\(\dfrac{6}{1^2+2^2}+\dfrac{10}{2^2+3^2}+\dfrac{14}{3^2+4^2}+...+\dfrac{398}{99^2.100^2}\)
Thực hiện phép tính
a) \(\dfrac{-0,8:\left(\dfrac{4}{5}.1,25\right)}{0,64-\dfrac{1}{5}}\)
b) ( 13,71 - \(1\dfrac{5}{6}\) ) . 6 - 6 . 13 . 17
c) \(\dfrac{\left(\dfrac{3}{5}+0,415+\dfrac{1}{200}\right):0,01}{30,75+\dfrac{1}{12}+3\dfrac{1}{6}}\)