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Ta có : \(A=\left(1-\frac{1}{2}\right)\left(1-\frac{1}{3}\right)\left(1-\frac{1}{4}\right).......\left(1-\frac{1}{2017}\right)\)
\(=\frac{1}{2}.\frac{2}{3}.\frac{3}{4}......\frac{2016}{2017}\)
\(=\frac{1.2.3......2016}{2.3.4.......2017}\)
\(=\frac{1}{2017}\)
Tìm x :
a) \(2.x.\frac{-3}{4}=-\frac{5}{12}\)
\(\Rightarrow2x=-\frac{5}{12}:-\frac{3}{4}\)
\(\Rightarrow2x=\frac{5}{9}\)
\(\Rightarrow x=\frac{5}{9}:2\)
\(\Rightarrow x=\frac{5}{18}\)
Vậy : \(x=\frac{5}{18}\)
b) \(\frac{2}{3}+\frac{1}{3}.x=7\)
\(\Rightarrow\frac{1}{3}.x=7-\frac{2}{3}\)
\(\Rightarrow\frac{1}{3}.x=\frac{19}{3}\)
\(\Rightarrow x=\frac{19}{3}:\frac{1}{3}\)
\(\Rightarrow x=19\)
Vậy : \(x=19\)
c) \(\left(4.x+\frac{1}{8}\right)=\frac{3}{10}\)
\(\Rightarrow4.x=\frac{3}{10}-\frac{1}{8}\)
\(\Rightarrow4.x=\frac{7}{40}\)
\(\Rightarrow x=\frac{7}{40}:4\)
\(\Rightarrow x=\frac{7}{160}\)
Vậy : \(x=\frac{7}{160}\)
d) \(\frac{1}{3}.x-5=1\frac{1}{2}\)
\(\Rightarrow\frac{1}{3}.x-5=\frac{3}{2}\)
\(\Rightarrow\frac{1}{3}.x=\frac{3}{2}+5\)
\(\Rightarrow\frac{1}{3}.x=\frac{13}{2}\)
\(\Rightarrow x=\frac{13}{2}:\frac{1}{3}\)
\(\Rightarrow x=\frac{39}{2}\)
Vậy : \(x=\frac{39}{2}\)
e) \(-\frac{2}{3}.x+\frac{1}{3}=-\frac{1}{2}\)
\(\Rightarrow-\frac{2}{3}.x=-\frac{1}{2}-\frac{1}{3}\)
\(\Rightarrow-\frac{2}{3}.x=-\frac{5}{6}\)
\(\Rightarrow x=-\frac{5}{6}:\left(-\frac{2}{3}\right)\)
\(\Rightarrow x=\frac{5}{4}\)
Vậy : \(x=\frac{5}{4}\)
a
\(5\frac{4}{7}:x+=13\)
\(\frac{39}{7}:x=13\)
\(x=\frac{39}{7}:13\)
\(x=\frac{3}{7}\)
\(\frac{4}{7}x=\frac{9}{8}-0,125\)
\(\frac{4}{7}x=1\)
\(x=1:\frac{4}{7}\)
\(x=\frac{7}{4}=1\frac{3}{4}\)
\(a,\frac{3}{4}-\frac{-1}{2}=x+\frac{1}{8}\Leftrightarrow x+\frac{1}{8}=\frac{5}{4}\Leftrightarrow x=\frac{5}{4}-\frac{1}{8}=\frac{9}{8}\)
\(b,\frac{x}{3}+\frac{3}{4}=\frac{2}{24}\Leftrightarrow\frac{x}{3}=\frac{2}{24}-\frac{3}{4}\Leftrightarrow\frac{x}{3}=\frac{-2}{3}\Leftrightarrow x=-2\)
\(c,\frac{-2}{3}-\left(-x\right)=\frac{1}{4}\Leftrightarrow-\left(-x\right)=\frac{1}{4}-\frac{-2}{3}\Leftrightarrow x=\frac{11}{12}\)
\(d,\frac{-5}{7}+x=\frac{-1}{2}+\frac{1}{3}\Leftrightarrow x=\frac{-1}{2}+\frac{1}{3}-\frac{-5}{7}=\frac{23}{42}\)
X : \(3\frac{1}{15}\)=\(1\frac{1}{2}\)
X : \(\frac{46}{15}\)=\(\frac{3}{2}\)
X = \(\frac{3}{2}\)X \(\frac{46}{15}\)
X = \(\frac{23}{5}\)
#)Giải :
\(x\div3\frac{1}{5}=1\frac{1}{2}\)
\(\Leftrightarrow x\div\frac{16}{5}=\frac{3}{2}\)
\(\Leftrightarrow x=\frac{24}{5}\)hay \(4\frac{4}{5}\)
\(\frac{2}{3}x-\frac{1}{2}x=\frac{5}{12}\)
\(\Leftrightarrow\left(\frac{2}{3}-\frac{1}{2}\right)x=\frac{5}{12}\)
\(\Leftrightarrow\frac{1}{6}x=\frac{5}{12}\)
\(\Leftrightarrow x=\frac{5}{2}\)
\(\left(\frac{1}{2}-1\right):\left(\frac{1}{2}-\frac{1}{3}-1\right)=\left(\frac{x}{2}-\frac{1}{4}\right):\left(\frac{2}{3}-1\right)\)
\(\Rightarrow-\frac{1}{2}:\left(\frac{1}{6}-1\right)=\left(\frac{x}{2}-\frac{1}{4}\right):\left(-\frac{1}{3}\right)\)
\(\Rightarrow-\frac{1}{2}:\left(-\frac{5}{6}\right)=\left(\frac{x}{2}-\frac{1}{4}\right):\left(-\frac{1}{3}\right)\)
\(\Rightarrow\left(\frac{x}{2}-\frac{1}{4}\right):\left(-\frac{1}{3}\right)=\frac{3}{5}\)
\(\Rightarrow\frac{x}{2}-\frac{1}{4}=\frac{3}{5}.\left(-\frac{1}{3}\right)\)
\(\Rightarrow\frac{x}{2}-\frac{1}{4}=-\frac{1}{5}\)
\(\Rightarrow\frac{x}{2}=-\frac{1}{5}+\frac{1}{4}\)
\(\Rightarrow\frac{x}{2}=\frac{1}{20}\)
\(\Rightarrow x.20=1.2\)
\(\Rightarrow x.20=2\)
\(\Rightarrow x=2:20\)
\(\Rightarrow x=0,1\)
\(\Leftrightarrow\frac{-1}{2}.\frac{-6}{5}=\frac{2?-1}{4}.-3\Leftrightarrow\frac{3}{5}=\frac{-6?+3}{4}\Leftrightarrow-30?+15=12\Leftrightarrow-30?=-3\Leftrightarrow?=\frac{1}{10}\)