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Vì 8a - 9b = 31 \(\Rightarrow\) a > b \(\Rightarrow\)\(\dfrac{a}{b}>1\)
Mà \(\dfrac{11}{17}< \dfrac{a}{b}< \dfrac{23}{29}\)
\(\Rightarrow\) không có cặp (a,b) nào thỏa mãn
Tìm các số tự nhiên a và b thỏa :
\(\dfrac{11}{17}< \dfrac{a}{b}< \dfrac{23}{29}v\text{à}8b-9a=31\)
Tìm phân số \(\frac{a}{b}\) biết \(\frac{11}{17}\)< \(\frac{a}{b}\)<\(\frac{23}{29}\)và 8a - 9b = 31
Tính :
a) \(\dfrac{17}{23}.\dfrac{8}{16}.\dfrac{23}{17}.\left(-80\right).\dfrac{3}{4}\)
b) \(\dfrac{5}{11}.\dfrac{18}{29}-\dfrac{5}{11}.\dfrac{8}{29}+\dfrac{5}{11}.\dfrac{19}{29}\)
c) \(\left(\dfrac{13}{23}+\dfrac{1313}{2323}-\dfrac{131313}{232323}\right).\left(\dfrac{1}{3}+\dfrac{1}{4}-\dfrac{7}{12}\right)\)
d) \(\dfrac{1^2}{1.2}.\dfrac{2^{2^{ }}}{2.3}.\dfrac{3^2}{3.4}.\dfrac{4^2}{4.5}.\dfrac{5^2}{5.6}.\dfrac{6^2}{6.7}.\dfrac{7^2}{7.8}.\dfrac{8^2}{8.9}.\dfrac{9^2}{9.10}\)
e) \(\dfrac{2^2}{3}.\dfrac{3^2}{8}.\dfrac{4^2}{15}.\dfrac{5^2}{24}.\dfrac{6^2}{35}\dfrac{7^2}{48}.\dfrac{8^2}{63}.\dfrac{9^2}{80}\)
bài 1 : so sánh :
a) \(\dfrac{23}{21}\)và\(\dfrac{21}{23}\)
b)\(\dfrac{19}{26}\)và \(\dfrac{21}{25}\)
bài 2 : sắp sếp các phân số sau từ bé đến lớn :
a)\(\dfrac{7}{36};\dfrac{24}{36};\dfrac{13}{36};\dfrac{1}{36};\dfrac{43}{36};\dfrac{36}{36}\)
b)\(\dfrac{-3}{10};\dfrac{-31}{100};\dfrac{-297}{1000};\dfrac{10000}{-3056}\)
c)\(\dfrac{13}{20};\dfrac{7}{20};\dfrac{9}{4};\dfrac{2}{5};\dfrac{1}{2}\)
d)\(\dfrac{13}{21};\dfrac{152}{17};\dfrac{13}{17};\dfrac{-5}{21}\)
e)\(\dfrac{-1}{2};\dfrac{3}{-4};\dfrac{-2}{3};\dfrac{4}{-5}\)
Tính :
\(B=\left(\dfrac{7}{19\cdot31}+\dfrac{5}{19\cdot43}+\dfrac{3}{23\cdot43}+\dfrac{11}{23\cdot57}\right)\div\left(\dfrac{1}{31}-\dfrac{1}{57}\right)\)
1. Tính :
A = \(\dfrac{17}{15}\) . \(\dfrac{-31}{125}\) . \(\dfrac{1}{2}\) . \(\dfrac{10}{17}\) . \(\dfrac{-1}{8}\)
B = ( \(\dfrac{11}{4}\) . \(\dfrac{-5}{9}\) - \(\dfrac{4}{9}\) . \(\dfrac{11}{4}\) ) . \(\dfrac{8}{33}\)
So sánh : a, \(\dfrac{29}{60}và\dfrac{15}{28}\) b, \(\dfrac{13}{30}và\dfrac{23}{42}\) c, \(\dfrac{13}{36}và\dfrac{14}{45}\) d, \(\dfrac{1919}{9595}và\dfrac{1111}{5050}\)
Bài 4 tìm n thuộc Z bt
a) \(\dfrac{255}{23}< n< \dfrac{438}{29}\)
b) \(\dfrac{-191}{14}< n< \dfrac{-125}{12}\)
giúp mk vs nha các bn
Bài 1 : Tính bằng cách hợp lí :
a ) A = \((\) \(\dfrac{\dfrac{1}{13}-\dfrac{1}{17}-\dfrac{1}{23}}{\dfrac{2}{13}-\dfrac{2}{17}-\dfrac{2}{23}}\) \()\) . \((\) \(\dfrac{\dfrac{1}{3}-0,25+0,2}{1\dfrac{1}{6}-0,875+0,7}\) \()\) + \(\dfrac{6}{7}\)
b ) B = 2000 : \([\) \((\) \(\dfrac{0,4-\dfrac{2}{9}+\dfrac{2}{11}}{1,4-\dfrac{7}{9}+\dfrac{7}{11}}\) \()\) . \((\) \(\dfrac{-1\dfrac{1}{6}+0,875-0,7}{\dfrac{1}{3}-0,25+\dfrac{1}{5}}\) \()\) \(]\)
c ) C = 10101 . \((\) \(\dfrac{5}{111111}+\dfrac{2}{222222}-\dfrac{4}{21.143.37}\) \()\)
Bài 2 : Tìm x :
a ) \(\dfrac{1}{2.5}+\dfrac{1}{5.8}+\dfrac{1}{8.11}+......+\dfrac{1}{125.155}-x=\dfrac{1}{310}\)
b ) \(1\dfrac{3}{5}+(\dfrac{\dfrac{2}{7}\dfrac{2}{17}\dfrac{2}{37}}{\dfrac{5}{7}\dfrac{5}{17}\dfrac{5}{37}}).\) x = \(\dfrac{16}{5}\)