How do you write #y=3x^2-9x# into vertex form?

1 Answer
Jul 6, 2018

#y=3(x-3/2)^2-27/4#

Explanation:

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

#•color(white)(x)y=a(x-h)^2+k#

#"where "(h,k)" are the coordinates of the vertex and a"#
#"is a multiplier"#

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

#y=3(x^2-3x)#

#color(white)(y)=3(x^2+2(-3/2)x color(red)(+9/4)color(red)(-9/4))#

#color(white)(y)=3(x-3/2)^2-27/4larrcolor(blue)"in vertex form"#