giải hệ ptr {2(x+y) – √x-1 = 12 {(x+y) + 3 √x-1 =13

Giải thích các bước giải:

$\left\{\begin{matrix}2(x+y)-\sqrt{x-1}=12\\x+y+3\sqrt{x-1}=13\end{matrix}\right.$`=>`$\left\{\begin{matrix}2(x+y)-\sqrt{x-1}=12\\2(x+y)+6\sqrt{x-1}=26\end{matrix}\right.$

`=>6sqrt(x-1)+sqrt(x-1)=26-12`

`=>7sqrt(x-1)=14`

`=>sqrt(x-1)=2`

`=>x-1=4=>x=5`

$\left\{\begin{matrix}2(x+y)-\sqrt{x-1}=12\\x+y+3\sqrt{x-1}=13\end{matrix}\right.$`=>`$\left\{\begin{matrix}6(x+y)-3\sqrt{x-1}=36\\x+y+3\sqrt{x-1}=13\end{matrix}\right.$

`=>6(x+y)+x+y=36+13`

`=>7(x+y)=49`

`=>x+y=7`

Mà `x=5=>y=2`

   Vậy `x=5;y=2.`