Help, I can't get this
There exist constants a, h and k such that
3x^2 + 12x + 4 - 2x^2 + 16x - 25 = a(x - h)^2 + k
for all real numbers Enter the ordered triple (a,h,k).
Simplify the left-hand side to x2+28x−21.
Now, notice that the right-hand side is just vertex form. This means that a is the coefficient of the x2 term (in this case it's 1) and that (h,k) is the vertex.
The vertex is located at x=−b2a=−14. Substituting this in gives us (−14)2+28(−14)−21=−217. So, the vertex is (−14,−217).
Thus, the ordered triple is just (1,−14,−217)