tìm x
\(\frac{20}{x}=\frac{x}{5}\)
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3 + \(\frac{3}{20}\)+ \(\frac{3}{13}\) + \(\frac{3}{2013}\)
X x = \(\frac{5}{3}\)
5 + \(\frac{5}{20}\) + \(\frac{5}{13}\) + \(\frac{5}{2013}\)
3 x ( 1 + \(\frac{1}{20}\) + \(\frac{1}{13}\) + \(\frac{1}{2013}\) )
X x = \(\frac{5}{3}\)
5 x ( 1 + \(\frac{1}{20}\) +\(\frac{1}{13}\) + \(\frac{1}{2013}\) )
X x \(\frac{3}{5}\) = \(\frac{5}{3}\) => X = \(\frac{25}{9}\) vậy X = \(\frac{25}{9}\)
Ta có : \(X.\frac{3+\frac{3}{20}+\frac{3}{13}+\frac{3}{2013}}{5+\frac{5}{20}+\frac{5}{13}+\frac{5}{2013}}=\frac{5}{3}\)
\(\Leftrightarrow X.\frac{3\left(1+\frac{1}{20}+\frac{1}{13}+\frac{1}{2013}\right)}{5\left(1+\frac{1}{20}+\frac{1}{13}+\frac{1}{2013}\right)}=\frac{5}{3}\)
\(\Leftrightarrow X.\frac{3}{5}=\frac{5}{3}\Rightarrow X=\frac{5}{3}:\frac{3}{5}=\frac{5}{3}.\frac{5}{3}=\frac{25}{9}\)
Có lẽ bạn viết đề sai.
Câu hỏi của Vũ Mai Linh - Toán lớp 7 - Học toán với OnlineMath
a ) Ta có : \(\frac{x+11}{10}+\frac{x+21}{20}+\frac{x+31}{30}=\frac{x+41}{40}+\frac{x+101}{5}\)
\(\Leftrightarrow\left(\frac{x+11}{10}-1\right)+\left(\frac{x+21}{10}-1\right)+\left(\frac{x+31}{30}-1\right)=\left(\frac{x+41}{40}-1\right)+\left(\frac{x+101}{50}-2\right)\)
\(\Leftrightarrow\frac{x+1}{10}+\frac{x+1}{20}+\frac{x+1}{30}=\frac{x+1}{40}+\frac{x+1}{50}\)
\(\Rightarrow\frac{x+1}{10}+\frac{x+1}{20}+\frac{x+1}{30}-\frac{x+1}{40}-\frac{x+1}{50}=0\)
\(\Leftrightarrow\left(x+1\right)\left(\frac{1}{10}+\frac{1}{20}+\frac{1}{30}-\frac{1}{40}-\frac{1}{50}\right)=0\)
Mà \(\left(\frac{1}{10}+\frac{1}{20}+\frac{1}{30}-\frac{1}{40}-\frac{1}{50}\right)\ne0\)
Nên x + 1 = 0
=> x = -1
\(x+\frac{3+\frac{3}{20}+\frac{3}{13}+\frac{3}{2013}}{5+\frac{5}{20}+\frac{5}{13}+\frac{5}{2013}}=\frac{9}{2}\)
\(x+\frac{3\times\left(1+\frac{1}{20}+\frac{1}{13}+\frac{1}{2013}\right)}{5\times\left(1+\frac{1}{20}+\frac{1}{13}+\frac{1}{2013}\right)}=\frac{9}{2}\)
\(x+\frac{3}{5}=\frac{9}{2}\)
\(x=\frac{39}{10}\)
\(x=3,9\)
\(x\cdot\frac{3+\frac{3}{20}+\frac{3}{13}+\frac{3}{2013}}{5+\frac{5}{20}+\frac{5}{13}+\frac{5}{2013}}=\frac{5}{3}\)
\(x\cdot\frac{3\cdot\left(1+\frac{1}{20}+\frac{1}{13}+\frac{1}{2013}\right)}{5\cdot\left(1+\frac{1}{20}+\frac{1}{13}+\frac{1}{2013}\right)}=\frac{5}{3}\)
\(x\cdot\frac{3}{5}=\frac{5}{3}\)
\(x=\frac{5}{3}:\frac{3}{5}\)
\(x=\frac{25}{9}\)
\(x.\frac{3+\frac{3}{20}+\frac{3}{13}+\frac{3}{2013}}{5+\frac{5}{20}+\frac{5}{13}+\frac{5}{2013}}=\frac{5}{3}\)
\(x.\frac{3.\left(1+\frac{1}{20}+\frac{1}{13}+\frac{1}{2013}\right)}{5.\left(1+\frac{1}{20}+\frac{1}{13}+\frac{1}{2013}\right)}=\frac{5}{3}\)
\(x.\frac{3}{5}=\frac{5}{3}\)
\(x=\frac{5}{3}:\frac{3}{5}\)
\(x=\frac{25}{9}\)
\(x.\frac{\frac{3}{20}+\frac{3}{13}+\frac{3}{2013}}{\frac{5}{20}+\frac{5}{13}+\frac{5}{2013}}=\frac{5}{3}\)
\(\Rightarrow x.\frac{3\left(\frac{1}{20}+\frac{1}{13}+\frac{1}{2013}\right)}{5\left(\frac{1}{20}+\frac{1}{13}+\frac{1}{2013}\right)}=\frac{5}{3}\)
\(\Rightarrow x.\frac{3}{5}=\frac{5}{3}\)
\(\Rightarrow x=\frac{5}{3}:\frac{3}{5}=\frac{25}{9}\)
vậy \(x=\frac{25}{9}\)
\(\Rightarrow x.\frac{3\left(\frac{1}{10}+\frac{1}{13}+\frac{1}{2012}\right)}{5\left(\frac{1}{10}+\frac{1}{13}+\frac{1}{2012}\right)}=\frac{5}{3}\)
\(\Rightarrow x.\frac{3}{5}=\frac{5}{3}\)
\(\Rightarrow x=\frac{25}{9}\)
Mình lỡ đánh nhầm 2 lần \(\frac{5}{14}\)nha :)) chỉ 1 lần thôi
\(\frac{x}{x+4}=\frac{5}{6}=>6x=5\left(x+4\right)=5x+20\)
\(=>6x-5x=20=>x=20\)
\(\frac{20}{x}=\frac{x}{5}\)
\(\Rightarrow20.5=x.x\)
\(\Rightarrow100=x^2\)
\(\Rightarrow10^2=x^2\)
\(\Rightarrow x=10\)
Vậy x = 10
=> x.x = 20.5
=> x^2 = 100
=> x^2 = 10^2
=> x = 10
Vậy x = 10