Answer: D. -13
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Work Shown:
y = x^2 + 8x + 3 is the same as y = 1x^2 + 8x + 3
It is in the form y = ax^2 + bx + c
a = 1
b = 8
c = 3
Plug the values of a and b into the formula below to get the x coordinate of the vertex (h,k)
h = -b/(2a)
h = -8/(2*1)
h = -8/2
h = -4
Plug this into the original equation to get its paired y value. This will get us the value of k
y = x^2 + 8x + 3
y = (-4)^2 + 8(-4) + 3
y = 16 - 32 + 3
y = -13
This is the smallest y output possible. Therefore it is the minimum. The minimum occurs at the vertex (h,k) = (-4, -13)
We know we are dealing with a minimum because a = 1 is positive forming a parabola that opens upward. If a < 0, then the parabola would open downward to yield a maximum.
