Here's what i got, for a parabola ax^2+bx+c the vertex's x equals -b/2a a=4, b=5 x= -5/2*4 refine = x = -5/8 plug in x = -5/8 to find the y value y=4(-5/8)^2+5(-5/8)-1 refine y= -41/16 therefore the parabola vertex is: (-5/8,-41/16) hopes this helps.
