Question #c5316

1 Answer
Oct 1, 2017

#(2,11),x=2#

Explanation:

#"given the equation of a parabola in standard form"#

#•color(white)(x)y=ax^2+bx+c color(white)(x);a!=0#

#"then the x-coordinate of the vertex which is also the"#
#"axis of symmetry is"#

#x_(color(red)"vertex")=-b/(2a)#

#f(x)=-x^2+4x+7" is in standard form"#

#"with "a=-1,b=4,c=7#

#rArrx_(color(red)"vertex")=-4/(-2)=2#

#"substitute this value into the equation for y-coordinate"#

#rArry_(color(red)"vertex")=-4+8+7=11#

#rArrcolor(magenta)"vertex "=(2,11)#

#"axis of symmetry is "x=2#