Question

giải hpt \(\left\{{}\begin{matrix}2x-y=3\\x^2-y=6\end{matrix}\right.\)

help mee

Answer 1

\(\left\{{}\begin{matrix}2x-y=3\left(1\right)\\x^2-y=6\left(2\right)\end{matrix}\right.\)

Trừ vế theo vế của (2) cho (1)\(\Leftrightarrow x^2-2x=3\Leftrightarrow x^2-2x-3=0\Leftrightarrow\left(x-3\right)\left(x+1\right)=0\Leftrightarrow\)\(\left[{}\begin{matrix}x=3\\x=-1\end{matrix}\right.\)\(\Leftrightarrow\)\(\left[{}\begin{matrix}y=3\\y=-5\end{matrix}\right.\)

Vậy (x;y)={(3;3);(-1;-5)}

Answer 2

x = y = 3

Thế vào :

a) 2.3-3 = 3

b ) 3^2-3 = 6