A=\(\dfrac{1}{2}+\dfrac{1}{6}+\dfrac{1}{12}+...+\dfrac{1}{9702}+\dfrac{1}{9900}\)
= \(\dfrac{1}{1.2}+\dfrac{1}{2.3}+\dfrac{1}{3.4}+...+\dfrac{1}{98.99}+\dfrac{1}{99.100}\)
=\(\left(1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+...+\dfrac{1}{98}-\dfrac{1}{99}+\dfrac{1}{99}-\dfrac{1}{100}\right)\)
= \(1-\dfrac{1}{100}\) = \(\dfrac{99}{100}\)
Hãy so sánh : \(\dfrac{1}{6}+\dfrac{1}{12}+\dfrac{1}{20}+\dfrac{1}{30}+\dfrac{1}{42}+...+\dfrac{1}{9900}\)với \(\dfrac{1}{2}\)
\(\dfrac{1}{2}\) + \(\dfrac{1}{6}\) + \(\dfrac{1}{12}\) + ........+ \(\dfrac{1}{9900}\) + \(\dfrac{1}{10100}\)
Giúp mình nha mọi người !!!!!!!!!!!Mình đang cần gấp
Tìm x biết
\(\dfrac{x-1}{12}+\dfrac{x-1}{20}+\dfrac{x-1}{30}+\dfrac{x-1}{42}+\dfrac{x-1}{56}+\dfrac{x-1}{72}=\dfrac{16}{9}\)
Help me!! Mk đang cần gấp
Help me
\(\dfrac{x+3}{5}-\dfrac{1}{y-1}=\dfrac{2}{5}\)
\(-1-\dfrac{7}{14}\le\dfrac{x}{3}\le1+\dfrac{12}{48}\)
\(\dfrac{2y+7}{y-2}\in Z\)
Cho A = \(\dfrac{1}{5}+\dfrac{1}{5^2}+\dfrac{1}{5^3}+...+\dfrac{1}{5^{2014}}\). Chứng minh A < \(\dfrac{1}{4}\)
Help me!
Bài 6 tính
\(A=\dfrac{1}{2}+\dfrac{1}{2^2}+\dfrac{1}{2^3}+...+\dfrac{1}{2^{10}}\)
\(F=\dfrac{1}{15}+\dfrac{1}{21}+\dfrac{1}{28}+...+\dfrac{1}{190}\)
\(G=\dfrac{12}{84}+\dfrac{12}{210}+\dfrac{12}{390}+...+\dfrac{12}{210}\)
Thực hện phép tính hợp lí( nếu có thể)
a,\(\left(3\dfrac{1}{5}-2\dfrac{1}{3}+\dfrac{5}{6}\right)\)-\(\left(1,5-\dfrac{2}{3}+\dfrac{1}{6}\right)\)
b,\(\dfrac{\left(3\dfrac{1}{5}.1,4-2,5.\dfrac{7}{108}\right):2\dfrac{7}{18}+4\dfrac{1}{2}.0,1}{70,5-5,28:7\dfrac{1}{2}}\)
HELP ME, MÌNH CẦN GẤP
Tính nhanh:
1) \(\dfrac{2}{15}.6\dfrac{5}{11}+\dfrac{5}{11}.\dfrac{-2}{15}-\dfrac{2}{15}.2015^0\)
2)\(\dfrac{5}{2.7}+\dfrac{3}{14.11}+ \dfrac{4}{11.7}+\dfrac{1}{14.15}+\dfrac{13}{15.16}\)
Các bạn giup mk với !!!Chiều nay mk đi học rồi!!Help me!!!!!!!!!!!!!!!!!!!!!!!
Bài 1: Tìm x, biết:
a, \(\left(x+\dfrac{1}{4}-\dfrac{1}{3}\right):\left(2+\dfrac{1}{6}-\dfrac{1}{4}\right)=\dfrac{7}{46}\)
b, \(\dfrac{13}{15}-\left(\dfrac{13}{21}+x\right).\dfrac{7}{12}=\dfrac{7}{10}\)
Bài 2: Thực hiện phép tính:
a, \(\left(2\dfrac{5}{6}+1\dfrac{4}{9}\right):\left(10\dfrac{1}{12}-9\dfrac{1}{2}\right)\)
b, 1\(\dfrac{5}{18}-\dfrac{5}{18}.\left(\dfrac{1}{15}+1\dfrac{1}{12}\right)\)
c, \(-\dfrac{1}{7}.\left(9\dfrac{1}{2}-8,75\right):\dfrac{2}{7}+0,625:1\dfrac{2}{3}\)
