Question #c5316
1 Answer
Oct 1, 2017
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#