Question

solve the system of equations. enter your answer as an ordered pair.
$\begin{cases}6x + 3y=-9\\-4x + y = 3end{cases}$
(-1,7)
(1,-1)
(1,1)
(-1,-1)

Explanation:

Step1: Isolate y in the second - equation

From $-4x + y=3$, we get $y = 4x + 3$.

Step2: Substitute y into the first equation

Substitute $y = 4x+3$ into $6x + 3y=-9$. So $6x+3(4x + 3)=-9$.
Expand the left - hand side: $6x+12x + 9=-9$.
Combine like terms: $18x+9=-9$.
Subtract 9 from both sides: $18x=-9 - 9=-18$.
Divide both sides by 18: $x=-1$.

Step3: Find the value of y

Substitute $x = - 1$ into $y = 4x + 3$. Then $y=4\times(-1)+3=-4 + 3=-1$.

Answer:

D. $(-1,-1)$