Question

(x+10)(\(\dfrac{720}{x}-6\))=720

giải pt

Answer 1

ĐK: ` x \ne 0`

`(x+10)(720/x-6)=720`

`<=>(720(x+10))/x-6(x+10)=720`

`<=>(720x+7200)/x-6x-60=720`

`<=>7200/x-6x=60`

`<=>7200-6x^2=60x`

`<=>` \(\left[{}\begin{matrix}x=30\\x=-40\end{matrix}\right.\)

Vậy `S={30;-40}`.

Answer 2

\((x+10)(\dfrac{720}{x}-6)=720\) (ĐK: 
⇔\(720x-6x^2+7200-60x=720x\) 

⇔\((x-30)(x+40)=0\)

⇔\(\left[\begin{array}{} x-30=0\\ x+40=0 \end{array} \right.\)⇔\(\left[\begin{array}{} x=30\\ x=40 \end{array} \right.\)

Vậy  .