The general vertex form for a parabola with vertex at #(a,b)# is
#color(white)("XXX")color(magenta)y=color(green)m(color(cyan)x-color(red)a)^2+color(blue)b#
For the vertex #(color(red)a,color(blue)b)=(color(red)(-5),color(blue)4)# this becomes
#color(white)("XXX")color(magenta)y=color(green)m(color(cyan)x-color(red)((-5)))^2+color(blue)4#
#color(white)("XXXX") =color(green)m(x+5)^2+color(blue)4#
Since this equation hold for the point #(color(cyan)x,color(magenta)y)=(color(cyan)6,color(magenta)125)#
#color(white)("XXX")color(magenta)(125)=color(green)m(color(cyan)6+5)^2+color(blue)(4#
#color(white)("XXXXX")=color(green)m * 11^2 +color(blue)4#
#color(white)("XXXXX")=121color(green)m +color(blue)4#
#rarrcolor(white)("X")121=121color(green)m#
#rarrcolor(white)("X")color(green)m=1#
and the equation is
#color(white)("XXX")color(magenta)y=color(green)1(color(cyan)x+5)^2+4#
