Question 153097
The Equation y=-4.9x^2+9x+15 describes the height of a diver,y, in metres at x seconds
a)Use the partial factored form to make a sketch of the parabola.
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I think you are trying to plot points.  That is not what "partial 
factored form" implies.
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-4.9x^2 + 9x = y-15
-4.9(x^2 - (9/4.9)x + (4.5/4.9)^2) = y - 15 -4.9(4.5/4.9)^2
-4.9(x-(4.5/4.9))^2 = y - 19.1326
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As you saw the y-intercept is (0,15)
As the partial factor form shows; the axis symmetry is x = (4.5/4.9)
Also f(4.5/4.9) = 19.133 gives you the coordinates of the vertex.

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Graph:
{{{graph(400,300,-10,10,-10,20,-4.9x^2+9x+15)}}}
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Cheers,
Stan H.