Question

Giả phương trình 100/x+2 - 80/x = 1/3

Answer 1

\(\dfrac{100}{x+2}-\dfrac{80}{x}=\dfrac{1}{3}\) \(\left(x\ne-2,x\ne0\right)\)

\(\Leftrightarrow\left[100x-80\left(x+2\right)\right]\cdot3=x\cdot\left(x+2\right)\)

\(\Leftrightarrow\left(20x-160\right)\cdot3=x^2+2x\)

\(\Leftrightarrow x^2-58x+480=0\)

\(\Leftrightarrow\left(x-10\right)\left(x-48\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=10\left(\text{Nhận}\right)\\x=48\left(\text{Nhận}\right)\end{matrix}\right.\)

 

Answer 2

\(\dfrac{100}{x+2}-\dfrac{80}{x}=\dfrac{1}{3}\Rightarrow300x-240\left(x+2\right)=x\left(x+2\right)=x\left(x+2\right)\\ \Leftrightarrow60x-480=x^2+2x\Leftrightarrow x^2-58x+480=0\Leftrightarrow\left(x-48\right)\left(x-10\right)=0\Leftrightarrow x=48.or.x=10\left(t.m\right)\)