Solve Linear Systems by Substitution
-$$\begin{array} { r }
2 x + 5 y = - 9 \
x = 2 y
\end{array}$$
A) $\{ ( - 2 , - 1 ) \}$
B) $\{ ( - 1 , - 2 ) \}$
C) $\{ ( - 2,1 ) \}$
D) $\{ ( - 1 , - 1 ) \}$

Question

Solve Linear Systems by Substitution
-$$\begin{array} { r } 
2 x + 5 y = - 9 \
x = 2 y
\end{array}$$
A) $\{ ( - 2 , - 1 ) \}$
B) $\{ ( - 1 , - 2 ) \}$
C) $\{ ( - 2,1 ) \}$
D) $\{ ( - 1 , - 1 ) \}$

Quizplus · Accepted Answer

Substitute $x = 2y$ into the first equation: $2(2y) + 5y = -9$, which simplifies to $4y + 5y = -9$, or $9y = -9$. Solving for $y$ gives $y = -1$. Substituting $y = -1$ back into $x = 2y$ gives $x = 2(-1) = -2$. Therefore, the solution is $(-2, -1)$.

Solve Linear Systems by Substitution - 2x+5y=−9x=2y\begin{array} { r } 2 x + 5 y = - 9 \\x = 2 y\end{array}2x+5y=−9x=2y​

Solve Linear Systems by Substitution
- $\begin{array} { r } 2 x + 5 y = - 9 \\x = 2 y\end{array}$