Respuesta :

to complete a square, both side add (half of b) squared.
in this case, b=6, half of 6 is 3, so 
x²+6x+3²=-7+3²
notice the left side is now a square: (x+3)²=2
solve: x+3=√2, or x+3=-√2
so x=-3+√2, or x=-3-√2

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