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(\(\frac{121}{122}\). \(\frac{123}{125}\)) .(\(\frac{1995}{1996}\).\(\frac{17}{16}\)- \(\frac{21}{25}\):\(\frac{16}{17}\)).(\(\frac{42}{30}\).\(\frac{75}{23}\)-\(\frac{19}{23}\).\(\frac{210}{38}\))
= (121/122 . 123/125) . ( 1995/1996 . 17/16 - 21/25 : 16/ 17) . 0
= 0
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2. a) \(3^{200}=\left(3^2\right)^{100}=9^{100}\)
\(2^{300}=\left(2^3\right)^{100}=8^{100}\)
Vì \(9^{100}>8^{100}\Rightarrow3^{200}>2^{300}\)
b) \(71^{50}=\left(71^2\right)^{25}=5041^{25}\)
\(37^{75}=\left(3^3\right)^{25}=27^{25}\)
Vì \(5041^{25}>27^{25}\Rightarrow71^{50}>37^{75}\)
c) \(\frac{201201}{202202}=\frac{201201:1001}{202202:1001}=\frac{201}{202}\)
\(\frac{201201201}{202202202}=\frac{201201201:1001001}{202202202:1001001}=\frac{201}{202}\)
Vì \(\frac{201}{202}=\frac{201}{202}\Rightarrow\frac{201201}{202202}=\frac{201201201}{202202202}\)
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Đè thừa một số \(\frac{25}{156}\),mk ko lại đề bài nhé
\(A=1-\frac{2+3}{2\cdot3}+.....+\frac{11+12}{11\cdot12}-\frac{12+13}{12\cdot13}\)
\(=1-\frac{1}{2}-\frac{1}{3}+\frac{1}{3}+\frac{1}{4}-...+\frac{1}{11}+\frac{1}{12}-\frac{1}{12}-\frac{1}{13}\)
\(=\frac{1}{2}-\frac{1}{13}=\frac{11}{26}\)
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\(a,\frac{3}{27}+\frac{1}{4}-\frac{1}{9}=\frac{3}{27}+\frac{1}{4}-\frac{3}{27}=\frac{3}{27}-\frac{3}{27}+\frac{1}{4}=\frac{1}{4}\)
\(b,\frac{72}{25}\cdot\frac{75}{36}=\frac{72\cdot75}{25\cdot36}=\frac{2\cdot36\cdot25\cdot3}{25\cdot36}=\frac{2\cdot3}{1\cdot1}=6\)
\(c,\frac{36}{49}:\frac{48}{14}=\frac{36}{49}\cdot\frac{14}{48}=\frac{36\cdot14}{49\cdot48}=\frac{3\cdot12\cdot2\cdot7}{7\cdot7\cdot4\cdot12}=\frac{3\cdot2}{7\cdot4}=\frac{6}{28}=\frac{3}{14}\)
\(d,\frac{39}{23}:26=\frac{39}{23}\cdot\frac{1}{26}=\frac{39}{23\cdot26}=\frac{3\cdot13}{23\cdot2\cdot13}=\frac{3}{23\cdot2}=\frac{3}{46}\)
\(e,45:\frac{15}{2}=\frac{45}{1}\cdot\frac{2}{15}=\frac{45\cdot2}{15}=\frac{3\cdot15\cdot2}{15}=\frac{6}{1}=6\)
\(g,\frac{57}{8}:\frac{3}{4}-\frac{15}{7}\cdot\frac{14}{25}=\frac{57\cdot4}{8\cdot3}-\frac{15\cdot14}{7\cdot25}=\frac{3\cdot19\cdot4}{2\cdot4\cdot3}-\frac{3\cdot5\cdot2\cdot7}{7\cdot5\cdot5}\)
\(=\frac{19}{2}-\frac{3\cdot2}{5}=\frac{95}{10}-\frac{12}{10}=\frac{83}{10}\)
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Xét : 6/13 - 6/17 + 18/23
= 4/13 . 3/2 - 4/17 . 3/2 + 12/23 . 3/2
= 3/2.(4/13-4/17+12/23)
=> D = 1/(3/2) = 2/3
Tk mk nha
\(D=\frac{\frac{4}{13}-\frac{4}{17}+\frac{12}{23}}{\frac{6}{13}-\frac{6}{17}+\frac{18}{23}}=\frac{4}{6}-\frac{4}{6}+\frac{12}{18}=\frac{2}{3}\)
-100/200+25/75+17/23+-6/36
= -1/2+1/3+17/23+-1/6
= (-1/2+1/3+-1/6)+17/23
= -1/3+17/23
= 28/69
cfghhg