A parabola opening up or down has vertex (0,0) and passes through (8, – 4). Write its equation in vertex form.

Recall the vertex form a parabola:
y = a(x - h)^2 + k , where (h, k) is the vetex.
Therefore, the equation of the parabola is y = a x^2.
All, we have to do now is solve for a. Since we know that the point (8, -4) lies on the parabola,
8 = a (-4)^2 => a = 1/2.
Therefore, the equation of the parabola is y = 1/2 x^2.
I found an answer from www.khanacademy.com
Vertex & axis of symmetry of a parabola (video) | Khan Academy
Sal rewrites a quadratic equation in vertex form and shows how it reveals the ... through. 6:10. Sal says "when x is equal to three it's also going to be equal to 8" ... he meant "when x is equal to 4" because we are calling each line ... I get that the parabola will open upward when a>0 and downward when a<0, but what if a=0?
For more information, see Vertex & axis of symmetry of a parabola (video) | Khan Academy
I found an answer from www.quora.com
What's the equation for a parabola with a stretch factor of 4 and ...
What's the equation for a parabola with a stretch factor of 4 and vertex of (6, 0)? ... What is the equation of the parabola with x intercepts -4 and 3 and that passes through (-2,7)? ... How do I write the equation in any form? ... Latus rectum joining the points (-4,2) and (2,1) with axis vertical and opening up? ... What is its focus?
For more information, see What's the equation for a parabola with a stretch factor of 4 and ...
I found an answer from answers.yahoo.com
A parabola opening up or down has vertex (0, – 3) and passes ...
Nov 19, 2020 ... A parabola opening up or down has vertex (0, – 3) and passes through (10, – 8). Write its equation in vertex form. Simplify any fractions.?
For more information, see A parabola opening up or down has vertex (0, – 3) and passes ...
I found an answer from www.khanacademy.org
Finding the vertex of a parabola in standard form (video) | Khan ...
Sal rewrites the equation y=-5x^2-20x+15 in vertex form (by completing the square) in order to identify the vertex of the corresponding parabola.
For more information, see Finding the vertex of a parabola in standard form (video) | Khan ...