`250/x - 250/(x+10) = 5/6`
ĐKXĐ : `x \ne 0 , x \ne - 10`
`⇔ (250.6(x+10))/(6x(x+10)) - (250.6x)/(6x(x+10)) = (5x(x+10))/(6x(x+10))`
`⇔ 1500(x+10) - 1500x = 5x(x+10)`
`⇔ 5x^2 + 50x = 15000`
`⇔ 5x^2 + 50x - 15000 = 0`
`⇔ 5(x-50)(x+60) = 0`
`⇔`\(\left[ \begin{array}{l}x-50=0\\x+60=0\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}x=50\text{(thỏa mãn)}\\x=-60\text{(thỏa mãn)}\end{array} \right.\)
Vậy `S = {50,-60}`
