Question

\(\dfrac{4800}{x}-\dfrac{4800}{x+100}=8\)

giải pt

Answer 1

ĐK: ` x\ne 0; x \ne -100`

`4800/x-4800/(x+100)=8`

`<=>1/x-1/(x+100) =1/600`

`<=> (x+100-x)/(x(x+100) = 1/600`

`<=> 100/(x(x+100))=1/600`

`<=> x^2+100x = 60000`

\(\left[{}\begin{matrix}x=200\\x=-300\end{matrix}\right.\)

Vậy...

Answer 2

`4800/x-4800/(x+10)=8`

`ĐK:x ne 0,x ne -10`

`pt<=>600/x-600/(x+10)=1`

`<=>(600x+6000-600x)/(x^2+10x)=1`

`<=>6000/(x^2+10x)=1`

`<=>x^2+10x=6000`

`<=>x^2+10x-6000=0`

`Delta'=25+6000=6025`

`<=>x_1=20,x_2=-30`