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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