Question

8 phần x+5 bằng 7 phần x-4

Answer 1

\(\dfrac{8}{x+5}=\dfrac{7}{x-4}\) ĐKXĐ : \(\left\{{}\begin{matrix}x+5\ne0\\x-4\ne0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x\ne-5\\x\ne4\end{matrix}\right.\)

`<=> (8(x-4))/((x+5)(x-4)) =(7(x+5))/((x+5)(x-4))`

`=> 8(x-4)=7(x+5)`

`<=>8x-32=7x+35`

`<=>8x-7x=35+32`

`<=>x= 67 (TM)`

Answer 2

\(\dfrac{8}{x+5}=\dfrac{7}{x-4}\left(x\ne-5;x\ne4\right)\)

suy ra: \(8\left(x-4\right)=7\left(x+5\right)\\ < =>8x-32=7x+35\\ < =>8x-7x=35+32\\ < =>x=67\left(tm\right)\)

Answer 3

\(\dfrac{8}{x+5}=\dfrac{7}{x-4}ĐK\left(x\ne5;4\right)\\ 8.\left(x-4\right)=7.\left(x+5\right)\\ 8x-32=7x+35\\ 8x-7x=35+32\\ x=67\)