How do you find the missing value to complete the square $x^2+2x$ ?

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Answer 1 · 2015-05-30T17:29:54

$(x+a)^2 = x^2+2ax+a^2$

We want $2ax$ to match $2x$ , so $a=1$ and the missing value is $a^2 = 1^2 = 1$

$x^2+2x+1 = (x+1)^2$

How do you find the missing value to complete the square x^2+2xx^2+2x?