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.

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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?

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What's the equation for a parabola with a stretch factor of 4 and ...

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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.?

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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 ...