Solve the system of equations using elimination.
-$$\left\{ \begin{array} { l }
2 x ^ { 2 } + x y - y ^ { 2 } = 3 \
x ^ { 2 } + 2 x y + y ^ { 2 } = 3
\end{array} \right.$$
A) $x = - \frac { 2 } { 3 } , y = \frac { 1 } { 3 } ; x = \frac { 2 \sqrt { 3 } } { 3 } , y = - \frac { 1 } { 3 }$

B) $x = \frac { 2 \sqrt { 3 } } { 3 } , y = \frac { \sqrt { 3 } } { 3 } ; x = - \frac { 2 \sqrt { 3 } } { 3 } , y = - \frac { \sqrt { 3 } } { 3 }$

C) $x = - \frac { 2 } { 3 } , y = - \frac { 1 } { 3 } ; x = \frac { 2 \sqrt { 3 } } { 3 } , y = \frac { 1 } { 3 }$

D) $x = \frac { 2 \sqrt { 3 } } { 3 } , y = - \frac { \sqrt { 3 } } { 3 } ; x = - \frac { 2 \sqrt { 3 } } { 3 } , y = \frac { \sqrt { 3 } } { 3 }$

Question

Solve the system of equations using elimination.
-$$\left\{ \begin{array} { l } 
2 x ^ { 2 } + x y - y ^ { 2 } = 3 \
x ^ { 2 } + 2 x y + y ^ { 2 } = 3
\end{array} \right.$$
A) $x = - \frac { 2 } { 3 } , y = \frac { 1 } { 3 } ; x = \frac { 2 \sqrt { 3 } } { 3 } , y = - \frac { 1 } { 3 }$

B) $x = \frac { 2 \sqrt { 3 } } { 3 } , y = \frac { \sqrt { 3 } } { 3 } ; x = - \frac { 2 \sqrt { 3 } } { 3 } , y = - \frac { \sqrt { 3 } } { 3 }$

C) $x = - \frac { 2 } { 3 } , y = - \frac { 1 } { 3 } ; x = \frac { 2 \sqrt { 3 } } { 3 } , y = \frac { 1 } { 3 }$

D) $x = \frac { 2 \sqrt { 3 } } { 3 } , y = - \frac { \sqrt { 3 } } { 3 } ; x = - \frac { 2 \sqrt { 3 } } { 3 } , y = \frac { \sqrt { 3 } } { 3 }$

Quizplus · Accepted Answer

By adding the two equations, we get $3x^2 + 3y^2 = 6$, which simplifies to $x^2 + y^2 = 2$. Subtracting the second equation from the first gives $x^2 - 2xy - y^2 = 0$, which simplifies to $(x - y)^2 = 0$, indicating $x = y$. Substituting $x = y$ into $x^2 + y^2 = 2$ gives $2x^2 = 2$, so $x^2 = 1$, leading to $x = \pm \sqrt{3}/3$. The solutions are $x = \frac{2\sqrt{3}}{3}, y = \frac{\sqrt{3}}{3}$ and $x = -\frac{2\sqrt{3}}{3}, y = -\frac{\sqrt{3}}{3}$.

Solve the System of Equations Using Elimination {2x2+xy−y2=3x2+2xy+y2=3\left\{ \begin{array} { l } 2 x ^ { 2 } + x y - y ^ { 2 } = 3 \\x ^ { 2 } + 2 x y + y ^ { 2 } = 3\end{array} \right.{2x2+xy−y2=3x2+2xy+y2=3​

Solve the System of Equations Using Elimination $\left\{ \begin{array} { l } 2 x ^ { 2 } + x y - y ^ { 2 } = 3 \\x ^ { 2 } + 2 x y + y ^ { 2 } = 3\end{array} \right.$