\(=\left(\dfrac{3}{2}-\dfrac{5}{6}+\dfrac{7}{12}\right)+\left(-\dfrac{9}{20}+\dfrac{11}{30}\right)+\left(\dfrac{-13}{42}+\dfrac{15}{56}\right)\)
\(=\dfrac{18-10+7}{12}+\dfrac{-27+22}{60}+\dfrac{-1}{24}\)
\(=\dfrac{15}{12}+\dfrac{-5}{60}+\dfrac{-1}{24}\)
\(=\dfrac{30-1+\left(-2\right)}{24}=\dfrac{27}{24}=\dfrac{9}{8}\)
Tính nhanh
\(\dfrac{15}{56}\) - \(\dfrac{13}{42}\) + \(\dfrac{11}{30}\) - \(\dfrac{9}{20}\) + \(\dfrac{7}{12}\) - \(\dfrac{5}{6}\) +\(\dfrac{3}{2}\)
Bài 1 : Thực hiện phép tính ( tính hợp lý nếu có thể )
a ) \(\dfrac{1}{12}+\dfrac{3}{4}\)
b ) \(\dfrac{-4}{7}.1\dfrac{1}{2}\)
c )\(\dfrac{7}{9}+\left(\dfrac{2}{3}+\dfrac{-7}{9}\right)\)
d )\(\dfrac{2}{3}-\dfrac{1}{3}:\dfrac{3}{4}\)
e )\(\dfrac{-7}{25}.\dfrac{11}{13}+\dfrac{-7}{25}.\dfrac{2}{13}\)
g )\(2\dfrac{2}{5}.0,25-\left(\dfrac{11}{20}+75\%\right):\dfrac{13}{5}\)
Bài 1. Thực hiện phép tính:
a) |5.0,6+\(\dfrac{2}{3}\)|- \(\dfrac{1}{3}\)
b)(0,25 - 1\(\dfrac{1}{4}\)) : 5 - \(\dfrac{1}{5}\).(-3)\(^2\)
c)\(\dfrac{14}{17}.\dfrac{7}{5}-\dfrac{-3}{17}:\dfrac{5}{7}\)
d)\(\dfrac{7}{16}+\dfrac{-9}{25}+\dfrac{9}{16}+\dfrac{-16}{25}\)
e)\(\dfrac{5}{6}+2\sqrt{\dfrac{4}{9}}\)
Thực hiện phép tính:
a) \(1\dfrac{13}{15}\). (-5)2. 3 + (\(\dfrac{8}{15}-\dfrac{19}{60}\)) : \(1\dfrac{23}{24}\)
b) \(\dfrac{\left(\dfrac{11^2}{200}+0.414:0.01\right)}{\dfrac{1}{12}-37.25+3\dfrac{1}{6}}\)
nhanh nhé mik cần gấp!
Thực hiện phép tính ( tính nhanh nếu có thể)
a)3\(\dfrac{14}{19}\) +\(\dfrac{13}{17}\)+\(\dfrac{35}{43}\)+ 6\(\dfrac{5}{19}\) + \(\dfrac{8}{43}\)
b) \(\dfrac{-5}{7}\) . \(\dfrac{2}{11}\) + \(\dfrac{-5}{7}\) . \(\dfrac{9}{11}\) + 1\(\dfrac{5}{7}\)
c) 11\(\dfrac{3}{13}\) - ( 2\(\dfrac{4}{7}\) + 5\(\dfrac{3}{13}\))
d) \(\dfrac{2}{7}\) . 5\(\dfrac{1}{4}\) - \(\dfrac{2}{7}\) . 3\(\dfrac{1}{4}\)
Tìm giá trị biểu thức:
a) P=\(\dfrac{5}{6}\)+\(\dfrac{5}{12}\)+\(\dfrac{5}{20}\)+\(\dfrac{5}{30}\)+\(\dfrac{5}{42}\)+\(\dfrac{5}{56}\)+\(\dfrac{5}{72}\)+\(\dfrac{5}{90}\)
b) A=\(\dfrac{3}{1.5}\)+\(\dfrac{3}{5.9}\)+\(\dfrac{3}{9.13}\)+...+\(\dfrac{3}{61.65}\). Chứng minh A<13.
Mik đag cần gấppp!!! Thanks!
Chứng tỏ rằng:
a) \(S=\dfrac{1}{5}+\dfrac{1}{13}+\dfrac{1}{14}+\dfrac{1}{15}+\dfrac{1}{61}+\dfrac{1}{62}+\dfrac{1}{63}< \dfrac{1}{2}\)
b) \(S=\dfrac{1}{41}+\dfrac{1}{42}+...+\dfrac{1}{80}>\dfrac{7}{12}\)
c) \(S=\dfrac{1}{2}+\dfrac{1}{2^2}+\dfrac{1}{2^3}+...+\dfrac{1}{2^{20}}< 1\)
d) \(\dfrac{49}{100}< S=\dfrac{1}{2^2}+\dfrac{1}{3^2}+\dfrac{1}{4^2}+...+\dfrac{1}{99^2}< 1\)
Các bạn giải ra từng bước dùm mik nha
Thanks m.n
1.Tính nhanh:
A= \(\dfrac{\dfrac{2}{3}-\dfrac{1}{4}+\dfrac{5}{11}}{\dfrac{5}{12}+1-\dfrac{7}{11}}\)
2. Cho: B =\(\dfrac{1}{4}+\dfrac{1}{5}+\dfrac{1}{6}+...+\dfrac{1}{19}\) .Hãy chứng tỏ rằng B > 1.
3. Rút gọn:
a) C= \(\left(1-\dfrac{1}{2}\right).\left(1-\dfrac{1}{3}\right).\left(1-\dfrac{1}{4}\right)....\left(1-\dfrac{1}{20}\right)\)
b) D= \(1+\dfrac{1}{2}+\dfrac{1}{2^2}+\dfrac{1}{2^3}+...+\dfrac{1}{2^{2012}}\)
4. So sánh: E=\(\dfrac{20^{10}+1}{20^{10}-1}\) và F =\(\dfrac{20^{10}-1}{20^{10}-3}\)
5. Tính giá trị của biểu thức:
M= \(\dfrac{\dfrac{3}{5}+\dfrac{3}{7}-\dfrac{3}{11}}{\dfrac{4}{5}+\dfrac{4}{7}-\dfrac{4}{11}}\)
Thực hiện phép tính ( tính nhanh nếu có thể)
a) \(\dfrac{-7}{25}\). \(\dfrac{11}{13}\)+ \(\dfrac{-7}{25}\). \(\dfrac{2}{13}\)- \(\dfrac{18}{25}\)
b) \(\dfrac{5}{7}\). \(\dfrac{1}{3}\) - \(\dfrac{5}{7}\). \(\dfrac{1}{4}\) - \(\dfrac{5}{7}\). \(\dfrac{1}{12}\)
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 : \(\dfrac{5}{12}\) - \(\left(\dfrac{-1}{2}\right)^2\)
