2 câu trả lời
`100/x - 100/(x+1) = 1/2 `
`<=> (100.(x+1))/(x.(x+1)) - 100x/(x.(x+1)) = 1/2`
`<=> (100x + 100)/(x^2 +x) - 100x/(x^2 +x ) =1/2`
`<=> (100x + 100 -100x)/(x^2 +x) =1/2`
`<=> 100/(x^2+x) =1/2`
`=> 200 = x^2 + x`
`<=> x^2 +x -200 = 0`
`<=>` \(\left[ \begin{array}{l}x=\frac{-1+3\sqrt{89}}{2}\\x=\frac{-1-3\sqrt{89}}{2}\end{array} \right.\)
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