Can someone explain to me where they got the +1 and -1 in the equation? They were breaking down how to transform a quadratic equation to vertex form and I understood most of it until they did that part. Then, they explained that it was the vertex... I'll post the picture below.

Question

anonymous · Answer

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anonymous · Answer

lol this is a dumb&%$$# way to do this problem

johnweldon1993 · Answer

^My thoughts exactly >.<

anonymous · Answer

half of 2 is 1, $1^2$ is 1 
if you add 1 you have to subtract 1
it is really not this damned complicated

anonymous · Answer

Yeah, I don't know why they teach the way they do lol. Thank you!