I really don't mean to be a nusance, I am new here and hope to be more of a contributer of this site rather that bothering people, so I apologize. I seem to have a hard time with ain taking a quadratic trinomial that cannot be factored and and converting it into a vertex formula [f(x)=(x-h)²+k].specific step

In this case:

f(x)= 2x² + 8x + 7

I know that the first step is to group the x terms leaving the leading coefficient out of the parenthesis such as:

f(x)= 2(x² + 4x) + 7

Next step is to take the middle term and square half the coefficient: (4/2)² and then add and subtract by that number.

f(x)= 2(x² + 4x+4-4) + 7

Now here is where it gets fuzzy for me, I read this online and here is the further step according to what I read:

Now,move the second -4 to the outside of the parenthesis, only now we have to consider that the outside coefficient isn't just a simple positive one. There's a 2 out there.

f(x) = 2(x² + 4x + 4)- 2() + 74

Question, is that-2that is underlined the-4that was outside the parentesis? And if so where did that four to the right of it come from? I'm stumped as to how it got there because if the-2was the-4inside the parenthesis and we have the+4inside the parenthesis, that(4)that is next to the-2seems to have crashed the party. I just can't figure out how it got there according to there steps and there seems to be no sufficient information as to how it got there, please explain.