How do you complete the square to solve $x^2 - 2x = 15$ ?

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Answer 1 · 2015-06-02T23:20:08

Given $x^2-2x=15$ add 1 to both sides to get:

$16 = x^2-2x+1 = (x-1)^2$

So $x-1 = +-sqrt(16) = +-4$

Add $1$ to both sides to get:

$x = 1+-4$

That is: $x = -3$ or $x=5$

How do you complete the square to solve x^2 - 2x = 15x^2 - 2x = 15?