Solve the system using the elimination-by-addition method. $$\left( \begin{array} { c }
x + 6 y = - 9 \
7 x - 6 y = 81
\end{array} \right)$$
A) ( 16, 4 )
B) ( 8, -4 )
C) ( 9, -3 )
D) ( 21, 9 )
E) ( 4, -8 )

Question

Solve the system using the elimination-by-addition method. $$\left( \begin{array} { c } 
x + 6 y = - 9 \
7 x - 6 y = 81
\end{array} \right)$$
A) ( 16, 4 )
B) ( 8, -4 )
C) ( 9, -3 )
D) ( 21, 9 )
E) ( 4, -8 )

Quizplus · Accepted Answer

Adding the two equations $x + 6y + 7x - 6y = -9 + 81$ eliminates $y$, resulting in $8x = 72$, so $x = 9$. Substituting $x = 9$ into the first equation, $9 + 6y = -9$, gives $6y = -18$, so $y = -3$. Therefore, the solution is $x = 9$, $y = -3$, which corresponds to choice C.

Solve the System Using the Elimination-By-Addition Method (x+6y=−97x−6y=81)\left( \begin{array} { c } x + 6 y = - 9 \\7 x - 6 y = 81\end{array} \right)(x+6y=−97x−6y=81​)

Solve the System Using the Elimination-By-Addition Method $\left( \begin{array} { c } x + 6 y = - 9 \\7 x - 6 y = 81\end{array} \right)$