The first equation from the previous system of equations is graphed. Graph the second equation to find the solution of the system of equations.
y = −2x + 4,
y = − 1/3x − 1

What is the solution to the system?

Vertex: V=(-2,-3)=(h,k)→h=-2, k=-3
The parabola is horizontal, then its equation has the form:
x=a(y-k)^2+h
x=a(y-(-3))^2+(-2)
x=a(y+3)^2-2

When the y-value is -2, the x-value is -5:
-5=a(-2+3)^2-2
-5=a(1)^2-2
-5=a(1)-2
-5=a-2
-5+2=a-2+2
-3=a
a=-3

The coefficient of the squared term in the parabola's equation is a=-3

Option D. -3