\(\dfrac{60}{x}-\dfrac{55}{21-x}=1\) (Điều kiện: \(x\ne0;x\ne21\))
\(\Leftrightarrow\dfrac{60\left(21-x\right)}{x\left(21-x\right)}-\dfrac{55x}{x\left(21-x\right)}=\dfrac{x\left(21-x\right)}{x\left(21-x\right)}\)
\(\Rightarrow1260-60x-55x=21x-x^2\)
\(\Leftrightarrow x^2-136x+1260=0\)
\(\Leftrightarrow x^2-126x-10x+1260=0\)
\(\Leftrightarrow x\left(x-126\right)-10\left(x-126\right)=0\)
\(\Leftrightarrow\left(x-126\right)\left(x-10\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-126=0\\x-10=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=126\\x=10\end{matrix}\right.\)
Đúng 0
Bình luận (1)
