Giá trị của biểu thức M=\dfrac{-9}{31}.\dfrac{5}{11}.\dfrac{-31}{9}.(-22)M=31−9.115.9−31.(−22) là
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Trong phép tính sau, giá trị của x là :
\(\dfrac{5}{9}\) : x = \(\dfrac{8}{9}\) - \(\dfrac{1}{5}\)
a. \(\dfrac{11}{6}\)
b. \(\dfrac{44}{30}\)
c. \(\dfrac{25}{31}\)
d. \(\dfrac{22}{15}\)
\(\dfrac{5}{9}:x=\dfrac{40}{45}-\dfrac{9}{45}\)
\(\dfrac{5}{9}:x=\dfrac{31}{45}\)
\(x=\dfrac{5}{9}:\dfrac{31}{45}\)
\(x=\dfrac{225}{279}=\dfrac{25}{31}\)
`=>C`
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Tính giá trị của đa thức \(\left(x^{31}-5x^{10}+3\right)^{2018}\)
tại x= 9-\(\dfrac{1}{\sqrt{\dfrac{9}{4}-\sqrt{5}}}+\dfrac{1}{\sqrt{\dfrac{9}{4}+\sqrt{5}}}\)
\(x=9-\dfrac{2}{\sqrt{9-4\sqrt{5}}}+\dfrac{2}{\sqrt{9+4\sqrt{5}}}=9-\dfrac{2}{\sqrt{\left(\sqrt{5}-2\right)^2}}+\dfrac{2}{\sqrt{\left(\sqrt{5}+2\right)^2}}\)
\(=9-\dfrac{2}{\sqrt{5}-2}+\dfrac{2}{\sqrt{5}+2}=9+\dfrac{2\left(\sqrt{5}-2-\sqrt{5}-2\right)}{\left(\sqrt{5}-2\right)\left(\sqrt{5}+2\right)}\)
\(=9+\left(-8\right)=1\)
\(\Rightarrow\left(1^{31}-5.1^{10}+3\right)^{2018}=\left(-1\right)^{2018}=1\)
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22 tháng 4 2023 lúc 19:53
\(\dfrac{-11}{31}\cdot\dfrac{-2}{17}+\dfrac{7}{31}\cdot\dfrac{-20}{17}-\dfrac{9}{17}\cdot\dfrac{11}{31}\)
=\(\dfrac{11}{31}\)*\(\left(\dfrac{-2}{17}-\dfrac{-9}{17}\right)\)+\(\dfrac{7}{31}\)*\(\dfrac{-20}{17}\)
=\(\dfrac{11}{31}\)*\(\dfrac{-7}{17}\)+\(\dfrac{7}{31}\)*\(\dfrac{-20}{17}\)
=\(\dfrac{-77}{512}\)+\(\dfrac{-140}{512}\)
=\(\dfrac{-217}{512}\)
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Tìm x ϵ Z, biết: dfrac{5}{17}+dfrac{-4}{9}+-dfrac{20}{31}+dfrac{12}{17}+dfrac{-11}{-31} dfrac{x}{9} ≤ dfrac{-3}{7}+dfrac{7}{15}+dfrac{4}{-7}+dfrac{8}{15}+dfrac{2}{3}
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Tìm x ϵ Z, biết:
\(\dfrac{5}{17}\)+\(\dfrac{-4}{9}\)+-\(\dfrac{20}{31}\)+\(\dfrac{12}{17}\)+\(\dfrac{-11}{-31}\)< \(\dfrac{x}{9}\) ≤ \(\dfrac{-3}{7}\)+\(\dfrac{7}{15}\)+\(\dfrac{4}{-7}\)+\(\dfrac{8}{15}\)+\(\dfrac{2}{3}\)
\(\Leftrightarrow-\dfrac{16}{279}< \dfrac{x}{9}< =\dfrac{2}{3}\)
\(\Leftrightarrow\dfrac{x}{9}=0\)
hay x=0
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\(\dfrac{\dfrac{28}{31}:\dfrac{7}{31}}{\dfrac{8}{9}:\dfrac{4}{9}}\)=
23 tháng 8 2023 lúc 15:37
Tìm giá trị của biểu thức: \(B=x+\dfrac{0,2-0,375+\dfrac{5}{11}}{-0,3+\dfrac{9}{16}-\dfrac{15}{22}}vớix=-\dfrac{1}{3}\)
\(B=x+\dfrac{0,2-0,375+\dfrac{5}{11}}{-0,3+\dfrac{9}{16}-\dfrac{15}{22}}\)
\(=x+\dfrac{\dfrac{1}{5}-\dfrac{3}{8}+\dfrac{5}{11}}{-\left(\dfrac{3}{10}-\dfrac{9}{16}+\dfrac{15}{22}\right)}\)
\(=x+\dfrac{\dfrac{1}{5}-\dfrac{3}{8}+\dfrac{5}{11}}{-\dfrac{3}{2}\left(\dfrac{1}{5}-\dfrac{3}{8}+\dfrac{5}{11}\right)}\)
\(=x+\dfrac{1}{-\dfrac{3}{2}}\)
\(=x+\dfrac{-2}{3}\)
Với \(x=-\dfrac{1}{3}\), ta được:
\(B=-\dfrac{1}{3}+\dfrac{-2}{3}=-\dfrac{3}{3}=-1\)
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Câu 1: Giá trị biểu thức M = \(\frac{-9}{31}.\frac{5}{11}.\frac{9}{31}.\left(-22\right)\)
Câu 2: Biết hai góc xOy và yOz là hai góc kề bù.Gọi Om,On lần lượt là tia phân giác của góc xOy và góc yOz.Khi đó số đo góc mOn là
Câu 3: Giá trị của x trong tỉ lệ thức 0,39:0,91 = x:\(16\frac{1}{3}\)
1)\(\dfrac{1}{2}+\dfrac{13}{19}-\dfrac{4}{9}+\dfrac{6}{19}+\dfrac{5}{18}\)
2)\(\dfrac{ }{\dfrac{-20}{23}+\dfrac{2}{3}-\dfrac{3}{23}+\dfrac{2}{5}+\dfrac{7}{15}}\)
3)\(\dfrac{ }{\dfrac{4}{3}+\dfrac{-11}{31}+\dfrac{3}{10}-\dfrac{20}{31}-\dfrac{2}{5}}\)
4)\(\dfrac{ }{\dfrac{5}{7}.\dfrac{5}{11}+\dfrac{5}{7}.\dfrac{2}{11}-\dfrac{5}{7}.\dfrac{14}{11}}\)
1) \(\dfrac{1}{2}+\dfrac{13}{19}-\dfrac{4}{9}+\dfrac{6}{19}+\dfrac{5}{18}\)
\(=\dfrac{1}{2}+\left(\dfrac{13}{19}+\dfrac{6}{19}\right)-\dfrac{4}{9}+\dfrac{5}{18}\)
\(=\dfrac{3}{2}-\dfrac{4}{9}+\dfrac{5}{18}\)
\(=\dfrac{19}{18}+\dfrac{5}{18}\)
\(=\dfrac{24}{18}\)
\(=\dfrac{4}{3}\)
2) \(\dfrac{-20}{23}+\dfrac{2}{3}-\dfrac{3}{23}+\dfrac{2}{5}+\dfrac{7}{15}\)
\(=\left(-\dfrac{20}{23}-\dfrac{3}{23}\right)+\dfrac{2}{3}+\dfrac{2}{5}+\dfrac{7}{15}\)
\(=-1+\dfrac{2}{3}+\dfrac{2}{5}+\dfrac{7}{15}\)
\(=-\dfrac{1}{3}+\dfrac{2}{5}+\dfrac{7}{15}\)
\(=\dfrac{1}{15}+\dfrac{7}{15}\)
\(=\dfrac{8}{15}\)
3) \(\dfrac{4}{3}+\dfrac{-11}{31}+\dfrac{3}{10}-\dfrac{20}{31}-\dfrac{2}{5}\)
\(=\left(\dfrac{-11}{31}-\dfrac{20}{31}\right)+\dfrac{4}{3}+\dfrac{3}{10}-\dfrac{2}{5}\)
\(=-1+\dfrac{4}{3}+\dfrac{3}{10}-\dfrac{2}{5}\)
\(=\dfrac{1}{3}+\dfrac{3}{10}-\dfrac{2}{5}\)
\(=\dfrac{1}{3}-\dfrac{1}{10}\)
\(=\dfrac{7}{30}\)
4) \(\dfrac{5}{7}.\dfrac{5}{11}+\dfrac{5}{7}.\dfrac{2}{11}-\dfrac{5}{7}.\dfrac{14}{11}\)
\(=\dfrac{5}{7}.\left(\dfrac{5}{11}+\dfrac{2}{11}-\dfrac{14}{11}\right)\)
\(=\dfrac{5}{7}.-\dfrac{7}{11}\)
\(=-\dfrac{35}{77}\)
\(=-\dfrac{5}{11}\)
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Quy đồng mẫu các phân số sâu
a)\(\dfrac{11}{8}\),\(\dfrac{-5}{9}\),\(\dfrac{-7}{12}\) b)\(\dfrac{31}{48}\),\(\dfrac{5}{10}\),\(\dfrac{-11}{16}\)
a: 11/8=99/72
-5/9=-40/72
-7/12=-42/72
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