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Ta có: \(\left(x-5\right)\frac{30}{100}=\frac{20x}{100}+5\)
\(\Rightarrow\left(x-5\right)\frac{3}{10}=\frac{x}{5}+5\)
\(\Rightarrow\frac{3x-15}{10}=\frac{25+x}{5}\)
\(\Rightarrow5\left(3x-15\right)=10\left(25+x\right)\)
\(\Rightarrow15x-75=250+10x\)
\(\Rightarrow15x-10x=250+75\)
\(\Rightarrow5x=325\Rightarrow x=\frac{325}{5}=65\)
\(\left(x-8\right).\frac{3}{10}=\frac{1}{5}x+5\)
\(\frac{3}{10}x-\frac{3}{2}=\frac{1}{5}x+5\)
\(\frac{3}{10}x=\frac{1}{5}x+6,5\)
\(\Rightarrow\frac{1}{10}x=6,5\)
\(x=\frac{6,5}{\frac{1}{10}}\)
\(x=65\)
Vậy \(x=65\)
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(x - 5).30/100 = 20x/100 + 5
<=>30x-150=20x+500 (quy đồng 2 vế rồi khử mẫu)
<=>10x=650
<=>x=65
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Ta có thể viết thành: (x - 5)3/10 = x/5 + 5
Nhân hai vế với 10, ta có : 3(x - 5) = (x/5 + 5) * 10
3x - 15 = 2x + 50
3x = 2x + 50 = 2x + 65
3x - 2x = 65
x = 65
Chúc bạn ht ~~
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\(\Leftrightarrow x-\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{98}-\frac{1}{99}\right)=\frac{1}{100}+\frac{1}{99}-\frac{1}{100}\)
\(\Leftrightarrow x-\frac{98}{99}=\frac{1}{99}\Leftrightarrow x=1\)
\(\left(x-5\right)\frac{3}{10}=\frac{1}{5}x+5\)
\(\frac{3}{10}x-\frac{3}{10}\cdot5=\frac{1}{5}x+5\)
\(\frac{3}{10}x-\frac{1}{5}x=\frac{3}{10}\cdot5+5\)
\(\frac{1}{10}x=\frac{13}{2}\)
\(x=65\)