Đại số lớp 7
Các câu hỏi tương tự
Cho A = \(1+\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{1}{4}+...+\dfrac{1}{4026},B=1+\dfrac{1}{3}+\dfrac{1}{5}+\dfrac{1}{7}+...+\dfrac{1}{4025}\)
So sánh \(\dfrac{A}{B}\) với \(1\dfrac{2013}{2014}\)
Tính:
a/dfrac{1+dfrac{1}{2}+dfrac{1}{3}+dfrac{1}{4}}{1-dfrac{1}{2}+dfrac{1}{3}-dfrac{1}{4}}:dfrac{3+dfrac{3}{2}+dfrac{3}{3}+dfrac{3}{4}}{2-dfrac{2}{2}+dfrac{2}{3}-dfrac{2}{4}}
b/dfrac{1+dfrac{1}{4}+dfrac{1}{1+dfrac{1}{4}}}{1-dfrac{1}{4}-dfrac{1}{1-dfrac{1}{4}}}
c/dfrac{dfrac{2}{5}-dfrac{7}{5}}{dfrac{2}{5}-dfrac{dfrac{3}{4}}{dfrac{3}{4}.dfrac{3}{7}-1}}-dfrac{1}{dfrac{3}{7}left(dfrac{3}{4}.dfrac{3}{7}.dfrac{2}{5}-dfrac{2}{5}-dfrac{3}{4}right)}
d/left(dfrac{dfrac{4}{3}}{2+dfrac{4}{3}}+dfrac{2-d...
Đọc tiếp
Tính:
a/\(\dfrac{1+\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{1}{4}}{1-\dfrac{1}{2}+\dfrac{1}{3}-\dfrac{1}{4}}:\dfrac{3+\dfrac{3}{2}+\dfrac{3}{3}+\dfrac{3}{4}}{2-\dfrac{2}{2}+\dfrac{2}{3}-\dfrac{2}{4}}\)
b/\(\dfrac{1+\dfrac{1}{4}+\dfrac{1}{1+\dfrac{1}{4}}}{1-\dfrac{1}{4}-\dfrac{1}{1-\dfrac{1}{4}}}\)
c/\(\dfrac{\dfrac{2}{5}-\dfrac{7}{5}}{\dfrac{2}{5}-\dfrac{\dfrac{3}{4}}{\dfrac{3}{4}.\dfrac{3}{7}-1}}-\dfrac{1}{\dfrac{3}{7}\left(\dfrac{3}{4}.\dfrac{3}{7}.\dfrac{2}{5}-\dfrac{2}{5}-\dfrac{3}{4}\right)}\)
d/\(\left(\dfrac{\dfrac{4}{3}}{2+\dfrac{4}{3}}+\dfrac{2-\dfrac{4}{3}}{\dfrac{4}{3}}\right).\left(\dfrac{\dfrac{2}{3}}{4+\dfrac{2}{3}}-\dfrac{4-\dfrac{2}{3}}{\dfrac{2}{3}}\right)\)
Giúp mik với các bạn ơi 1 bài thôi cug đc.
Bài 1: Cho A= \(\dfrac{1}{5}-\dfrac{1}{7}+\dfrac{1}{17}-\dfrac{1}{31}+\dfrac{1}{65}-\dfrac{1}{127}\)
So sánh A với \(\dfrac{1}{6}\)
Bài 2: Cho A = \(\dfrac{326}{1955}+\dfrac{988}{1975}+\dfrac{662}{1985}\) và B = \(\dfrac{3951}{3950}+\dfrac{1}{5955}+\dfrac{1}{11730}\)
So sánh A với B
dfrac{x+4}{2000}+dfrac{x+3}{2001}dfrac{x+2}{2002}+dfrac{x+1}{2003}
1/* Chứng minh rằng:
dfrac{1}{1times2}+dfrac{1}{3times4}+dfrac{1}{5times6}+...dfrac{1}{49times50}dfrac{1}{26}+dfrac{1}{27}+dfrac{1}{28}+..+dfrac{1}{50}
2/* Cho:
Adfrac{1}{1times2}+dfrac{1}{3times4}+dfrac{1}{5times6}+.....+dfrac{1}{99times100}. Chứng minh rằng:dfrac{7}{12} Adfrac{5}{6}
Các bn giúp mk những bài này nha!
Đọc tiếp
\(\dfrac{x+4}{2000}+\dfrac{x+3}{2001}=\dfrac{x+2}{2002}+\dfrac{x+1}{2003}\)
1/* Chứng minh rằng:
\(\dfrac{1}{1\times2}+\dfrac{1}{3\times4}+\dfrac{1}{5\times6}+...\dfrac{1}{49\times50}=\dfrac{1}{26}+\dfrac{1}{27}+\dfrac{1}{28}+..+\dfrac{1}{50}\)
2/* Cho:
A=\(\dfrac{1}{1\times2}+\dfrac{1}{3\times4}+\dfrac{1}{5\times6}+.....+\dfrac{1}{99\times100}\). Chứng minh rằng:\(\dfrac{7}{12}< A>\dfrac{5}{6}\)
Các bn giúp mk những bài này nha!
1/ Tính
dfrac{left(1+2+3+...+100right).left(dfrac{1}{3}-dfrac{1}{5}-dfrac{1}{7}-dfrac{1}{9}right).left(6,3.12-21.3,6right)}{dfrac{1}{2}+dfrac{1}{3}+dfrac{1}{4}+...+dfrac{1}{100}}
2/ Tìm x:
dfrac{x+4}{2000}+dfrac{x+3}{2001}dfrac{x+2}{2002}+dfrac{x+1}{2003}
3/ Cho Adfrac{1}{1.2}+dfrac{1}{3.4}+dfrac{1}{5.6}+...+dfrac{1}{99.100}
Chứng minh: dfrac{7}{12} A dfrac{5}{6}
4/ Tìm a,bvarepsilon Q:a+ba.ba:b
Giúp mik nha mai mik cần rồi.
Đọc tiếp
1/ Tính
\(\dfrac{\left(1+2+3+...+100\right).\left(\dfrac{1}{3}-\dfrac{1}{5}-\dfrac{1}{7}-\dfrac{1}{9}\right).\left(6,3.12-21.3,6\right)}{\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{1}{4}+...+\dfrac{1}{100}}\)
2/ Tìm x:
\(\dfrac{x+4}{2000}+\dfrac{x+3}{2001}=\dfrac{x+2}{2002}+\dfrac{x+1}{2003}\)
3/ Cho \(A=\dfrac{1}{1.2}+\dfrac{1}{3.4}+\dfrac{1}{5.6}+...+\dfrac{1}{99.100}\)
Chứng minh: \(\dfrac{7}{12}< A< \dfrac{5}{6}\)
4/ Tìm \(a,b\varepsilon Q:a+b=a.b=a:b\)
Giúp mik nha mai mik cần rồi.
Thực hiện phép tính:
a) 1dfrac{4}{23}+dfrac{5}{21}-dfrac{4}{23}+0,5+dfrac{16}{21}
b) dfrac{3}{7}.19dfrac{1}{3}-dfrac{3}{7}.33dfrac{1}{3}
c) left(15dfrac{1}{4}+2010right):left(-dfrac{5}{7}right)-left(25dfrac{1}{4}+2016right):left(-dfrac{5}{7}right)
d) left(2017-dfrac{3}{7}+dfrac{9}{11}right)-left(2016-dfrac{3}{7}+dfrac{8}{17}right)-left(2015+dfrac{9}{11}-dfrac{8}{17}right)
Đọc tiếp
Thực hiện phép tính:
a) \(1\dfrac{4}{23}+\dfrac{5}{21}-\dfrac{4}{23}+0,5+\dfrac{16}{21}\)
b) \(\dfrac{3}{7}.19\dfrac{1}{3}-\dfrac{3}{7}.33\dfrac{1}{3}\)
c) \(\left(15\dfrac{1}{4}+2010\right):\left(-\dfrac{5}{7}\right)-\left(25\dfrac{1}{4}+2016\right):\left(-\dfrac{5}{7}\right)\)
d) \(\left(2017-\dfrac{3}{7}+\dfrac{9}{11}\right)-\left(2016-\dfrac{3}{7}+\dfrac{8}{17}\right)-\left(2015+\dfrac{9}{11}-\dfrac{8}{17}\right)\)
15 tháng 12 2021 lúc 21:44
Thực hiện phép tính (tính nhanh nếu có thể):
a) \(\left(\dfrac{1}{2}-\dfrac{1}{3}\right)-\left(\dfrac{5}{3}-\dfrac{3}{2}\right)+\left(\dfrac{7}{3}-\dfrac{5}{2}\right)\)
b) \(\left(\dfrac{3}{4}-1\dfrac{1}{6}\right)^2:\sqrt{\dfrac{25}{144}}\)
1. Tính:
a. dfrac{-1}{4}+dfrac{5}{6} b. dfrac{5}{12}+dfrac{-7}{8} c. dfrac{-7}{6}+dfrac{-3}{10} d. dfrac{-3}{7}+dfrac{5}{6}
2. Tính :
a. dfrac{2}{14}-dfrac{5}{2} b. dfrac{-13}{12}-dfrac{5}{18} c. dfrac{-2}{5}-dfrac{-3}{11} d. 0,6--1dfrac{2}{3}
3. Tính :
a. dfrac{-1}{39}+dfrac{-1}{52} b. dfr...
Đọc tiếp
1. Tính:
a. \(\dfrac{-1}{4}+\dfrac{5}{6}\) b. \(\dfrac{5}{12}+\dfrac{-7}{8}\) c. \(\dfrac{-7}{6}+\dfrac{-3}{10}\) d. \(\dfrac{-3}{7}+\dfrac{5}{6}\)
2. Tính :
a. \(\dfrac{2}{14}-\dfrac{5}{2}\) b. \(\dfrac{-13}{12}-\dfrac{5}{18}\) c. \(\dfrac{-2}{5}-\dfrac{-3}{11}\) d. \(0,6--1\dfrac{2}{3}\)
3. Tính :
a. \(\dfrac{-1}{39}+\dfrac{-1}{52}\) b. \(\dfrac{-6}{9}-\dfrac{12}{16}\) c. \(\dfrac{-3}{7}-\dfrac{-2}{11}\) d.\(\dfrac{1}{1.2}+\dfrac{1}{2.3}+\dfrac{1}{3.4}+...+\dfrac{1}{8.9}+\dfrac{1}{9.10}\)
a) dfrac{1}{3}-dfrac{3}{5}+dfrac{5}{7}-dfrac{7}{9}+dfrac{9}{11}-dfrac{11}{13}+dfrac{13}{15}+dfrac{11}{13}-dfrac{9}{11}+dfrac{7}{9}-dfrac{5}{7}+dfrac{3}{5}-dfrac{1}{3}
b)dfrac{1}{99}-dfrac{1}{99.98}-dfrac{1}{98.97}-dfrac{1}{97.96}-.....-dfrac{1}{3.2}-dfrac{1}{2.1}
c) dfrac{1}{1.3}+dfrac{1}{3.5}+.....+dfrac{1}{left(2n-1right)left(2n+1right)}+......+dfrac{1}{255.257}
Đọc tiếp
a) \(\dfrac{1}{3}-\dfrac{3}{5}+\dfrac{5}{7}-\dfrac{7}{9}+\dfrac{9}{11}-\dfrac{11}{13}+\dfrac{13}{15}+\dfrac{11}{13}-\dfrac{9}{11}+\dfrac{7}{9}\)\(-\dfrac{5}{7}+\dfrac{3}{5}-\dfrac{1}{3}\)
b)\(\dfrac{1}{99}-\dfrac{1}{99.98}-\dfrac{1}{98.97}-\dfrac{1}{97.96}-.....-\dfrac{1}{3.2}-\dfrac{1}{2.1}\)
c) \(\dfrac{1}{1.3}+\dfrac{1}{3.5}+.....+\dfrac{1}{\left(2n-1\right)\left(2n+1\right)}+......+\dfrac{1}{255.257}\)