What is the x coordinate of the vertex of the parabola who equation is y = 3x ^ 2 + 9x?

The given equation y = 3x^2+9x is in the form y = ax^2+bx+c

Since a = 3 and b = 9, this means,
h = -b/(2a)
h = -9/(2*3)
h = -9/6
h = -3/2
h = -1.5
is the x coordinate of the vertex (h,k)

As a fraction, the answer is -3/2
In decimal form, that answer is -1.5
(use long division or a calculator to find that -3/2 = -1.5)

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