What is the x-coordinate of the vertex of the parabola whose equation is y = 3x2 + 12x + 5?

The x-coordinate of the vertex of this parabola would be -2. 

You can find the x-coordinate of any parabola by using the formula -b/2a, in which a is the number attached to x^2 and b is the number attached to x. 

In this case a = 3 (since it is attached to x^2) and b = 12 (because it is attached to x). So we can solve using these pieces of information.

-b/2a = x
-(12)/2(2) = x
-12/6 = x
-2 = x

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