A=2/3*5 + 2/5*7 + 2/7*9 + 2/9*11
A=1/3 - 1/5 +1/5 -1/7 + 1/7 - 1/9 + 1/9 - 1/11
A=1/3 - 1/11
A=8/33
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\(\frac{2}{15}+\frac{2}{35}+\frac{2}{63}+\frac{2}{99}\)+...+\(\frac{2}{399}\)
the value ò \(\frac{2}{3}+\frac{2}{15}+\frac{2}{35}+\frac{2}{63}+\frac{2}{99}\) is...
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Tinh cach bieu thuc sau
A=2+4-6-8+10+12-14-16+....+210+214-216-218
B=\(2^{2013}-2^{2012}-2^{2011}-2^{2010}-...-2-1\)
C=\(\frac{2}{15}+\frac{2}{35}+\frac{2}{63}+\frac{2}{99}\)
\(A=\frac{1}{3}+\frac{13}{15}+\frac{33}{35}+\frac{61}{63}+\frac{97}{99}+\frac{141}{143}\)
1/ Tính:a) frac{1}{2}-2left(frac{1}{2cdot4}+frac{1}{4cdot6}+frac{1}{6cdot8}+...+frac{1}{48cdot50}right)b) frac{-1}{3}+frac{-1}{15}+frac{-1}{63}+...+frac{-1}{9999}c) frac{8}{9}-frac{1}{72}-frac{1}{56}-frac{1}{42}-...-frac{1}{6}-frac{1}{2}d) 1-frac{1}{2cdot5}-frac{1}{5cdot8}-frac{1}{8cdot11}-...-frac{1}{89cdot92}-frac{1}{92cdot95}2/ Tìm x:3x-frac{1}{3}-frac{1}{15}-frac{1}{35}-frac{1}{63}-frac{1}{99}0
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1/ Tính:
a) \(\frac{1}{2}-2\left(\frac{1}{2\cdot4}+\frac{1}{4\cdot6}+\frac{1}{6\cdot8}+...+\frac{1}{48\cdot50}\right)\)
b) \(\frac{-1}{3}+\frac{-1}{15}+\frac{-1}{63}+...+\frac{-1}{9999}\)
c) \(\frac{8}{9}-\frac{1}{72}-\frac{1}{56}-\frac{1}{42}-...-\frac{1}{6}-\frac{1}{2}\)
d) \(1-\frac{1}{2\cdot5}-\frac{1}{5\cdot8}-\frac{1}{8\cdot11}-...-\frac{1}{89\cdot92}-\frac{1}{92\cdot95}\)
2/ Tìm x:
\(3x-\frac{1}{3}-\frac{1}{15}-\frac{1}{35}-\frac{1}{63}-\frac{1}{99}=0\)
Tìm x:
\(3x-\frac{1}{3}-\frac{1}{15}-\frac{1}{35}-\frac{1}{63}-\frac{1}{99}=0\)
\(A=\frac{1}{3}+\frac{13}{15}+\frac{33}{35}+\frac{61}{63}+\frac{97}{99}+\frac{141}{143}+\frac{193}{195}\)
Chứng tỏ rằng A không là số nguyên.
tính
\(\frac{\left(1+2+3+....+99+100\right).\left(\frac{1}{2}-\frac{1}{3}-\frac{1}{7}-\frac{1}{9}\right).\left(63\times1,2-21\times3,6\right)}{1-2+3-4+....+99-100}\)
Kiểm tra bài : Nhân, chia số hữu tỉThực hiện phép tính :(1) -frac{3}{2}.frac{7}{10}frac{-3.7}{2.10}frac{-21}{20}(2) frac{-5}{3}.frac{6}{11}frac{-5.6}{3.11}frac{-30}{33}(3) 2frac{1}{3}.left(-1frac{2}{3}right)frac{7}{3}.left(-frac{5}{3}right)frac{7.left(-5right)}{3.3}-frac{35}{9}(4) frac{9}{10}:left(-frac{15}{11}right)frac{9}{10}.left(frac{-11}{15}right)frac{9.left(-11right)}{10.15}-frac{99}{150}-frac{33}{50}(5) left(-1right):frac{3}{8}frac{left(-1right).8}{3}-frac{8}{3}(6) frac{1}{2}.left(-frac{5...
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Kiểm tra bài : Nhân, chia số hữu tỉ
Thực hiện phép tính :
(1) \(-\frac{3}{2}.\frac{7}{10}=\frac{-3.7}{2.10}=\frac{-21}{20}\)
(2) \(\frac{-5}{3}.\frac{6}{11}=\frac{-5.6}{3.11}=\frac{-30}{33}\)
(3) \(2\frac{1}{3}.\left(-1\frac{2}{3}\right)=\frac{7}{3}.\left(-\frac{5}{3}\right)=\frac{7.\left(-5\right)}{3.3}=-\frac{35}{9}\)
(4) \(\frac{9}{10}:\left(-\frac{15}{11}\right)=\frac{9}{10}.\left(\frac{-11}{15}\right)=\frac{9.\left(-11\right)}{10.15}=-\frac{99}{150}=-\frac{33}{50}\)
(5) \(\left(-1\right):\frac{3}{8}=\frac{\left(-1\right).8}{3}=-\frac{8}{3}\)
(6) \(\frac{1}{2}.\left(-\frac{5}{4}\right).\frac{8}{7}=\frac{1.\left(-5\right)}{2.4}.\frac{8}{7}=-\frac{5}{8}.\frac{8}{7}=-\frac{5.8}{8.7}=-\frac{5}{7}\)
(7) \(\frac{-9}{2}.\frac{2}{18}.\frac{1}{7}=\left(-\frac{9}{2}.\frac{2}{18}\right).\frac{1}{7}=\left(-\frac{9.2}{2.18}\right).\frac{1}{7}=-\frac{18}{36}.\frac{1}{7}=-\frac{18.1}{36.7}=-\frac{1}{14}\)
(8) \(\left(\frac{9}{2}-\frac{1}{3}\right).\frac{6}{17}=\left(\frac{27}{6}-\frac{2}{6}\right).\frac{6}{17}=\frac{27-2}{6}.\frac{6}{17}=\frac{25}{6}.\frac{6}{17}=\frac{25.6}{6.17}=\frac{25}{17}\)
(9) \(\left(-\frac{12}{13}:\frac{36}{39}\right).\frac{3}{5}=\left(-\frac{12}{13}.\frac{39}{36}\right).\frac{3}{5}=\left(\frac{-12.39}{13.36}\right).\frac{3}{5}=-\frac{1.3}{5}=-\frac{3}{5}\)
(10) \(\left(-\frac{3}{7}+\frac{7}{9}\right):\frac{4}{7}+\left(-\frac{4}{7}+\frac{2}{9}\right):\frac{4}{7}=\left(\left(-\frac{3}{7}+\frac{7}{9}\right)+\left(-\frac{4}{7}+\frac{2}{9}\right)\right):\frac{4}{7}\)
\(=\left(\left(-\frac{27}{63}+\frac{49}{63}\right)+\left(-\frac{36}{63}+\frac{14}{63}\right)\right):\frac{4}{7}=\left(\left(-\frac{27+49}{63}\right)+\left(\frac{-36+14}{63}\right)\right):\frac{4}{7}\)
\(=\left(\left(\frac{22}{63}\right)+\left(-\frac{22}{63}\right)\right):\frac{4}{7}\)
\(=\frac{22+\left(-22\right)}{63}:\frac{4}{7}=\frac{0}{63}:\frac{4}{7}=0\)
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