Question 448426
<pre><font face = "Tohoma" size = 4 color = "indigo"><b> 
Hi
y= 2x^2-4x -16
Note: the vertex form of a parabola, {{{y=a(x-h)^2 +k}}} where(h,k) is the vertex
y= 2x^2-4x -16   |Completing the square
y = 2[(x-1)^2 - 1] -16
y = 2(x-1)^2 - 2 -16
y = 2(x-1)^2 -18  Vertex(1,-18) a = 2 > 0 parabola opens upward
Line  of symmetry is x = 1
x-intercepts when y = 0 are also the solutions for the quadratic equation
 2(x-1)^2 = 18
    x-1 = ± {{{sqrt(9)}}}
      x = 1 ± 3     x = 4 or x = -2
{{{drawing(300,300, -20, 20, -20, 20, blue(line(1,20,1,20)), grid(1),
circle(1, -18,0.6),
circle(4, 0,0.6),
circle(-2, 0,0.6),
graph( 300, 300,  -20, 20, -20, 20,0, 2x^2 - 4x -16))}}}