10/x + 12 (1/80 - 1/x) = 2/15 tìm x

2 câu trả lời

$ĐKXĐ:x\neq 0$

$\dfrac{10}{x}+12(\dfrac{1}{80}-\dfrac{1}{x})=\dfrac{2}{15}$ 

$⇔\dfrac{10}{x}+\dfrac{12}{80}-\dfrac{12}{x}=\dfrac{2}{15}$ 

$⇔\dfrac{10}{x}+\dfrac{3}{20}-\dfrac{12}{x}=\dfrac{2}{15}$ 

$⇔\dfrac{-2}{x}+\dfrac{3}{20}=\dfrac{2}{15}$ 

$⇔\dfrac{-2}{x}=\dfrac{-1}{60}$ 

$⇔x=120$

Vậy `S={120}`