How do you write #y=2x^2-9x-5# in vertex form?

1 Answer
Jim G.
Sep 7, 2017

#y=2(x-9/4)^2-121/8#

Explanation:

#"the equation of a parabola in "color(blue)"vertex form"# is.

#color(red)(bar(ul(|color(white)(2/2)color(black)(y=a(x-h)^2+k)color(white)(2/2)|)))#
where (h , k ) are the coordinates of the vertex and a is a constant.

#"to obtain this form "color(blue)"complete the square"#

#y=2(x^2-9/2x)-5larr" coefficient of "x^2" equal to 1"#

#color(white)(y)=2(x^2+2(-9/4)x+81/16-81/16)-5#

#color(white)(y)=2(x-9/4)^2-81/8-5#

#color(white)(y)=2(x-9/4)^2-121/8#

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