Three term quadratic?

Express x^2 - 2x - 15 in the form (x+a)^2 + b.

1 Answer
Jim G.
Sep 12, 2017

(x-1)^2-16

Explanation:

"using the method of "color(blue)"completing the square"

• " ensure the coefficient of the "x^2" term is 1"

• " add/subtract "(1/2"coefficient of x-term")^2" to "x^2-2x

rArrx^2-2x-15

=x^2+2(-1)xcolor(red)(+1)color(red)(-1)-15

=(x-1)^2-16larra=-1,b=-16

color(blue)"As a check for you"

(x-1)^2-16

=x^2-2x+1-16

=x^2-2x-15

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