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Student estimates, then calculates exactly and symbolically the value of $k$ for a parabola $y = k x^2$ which passes through a given point.

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The equation for a parabola with vertex at the origin is given by the general equation

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$y=kx^2$.  

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This equation describes an infinite family of parabolas, each corresponding to a different value of $k$.

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Substituting in the known coordnates of the point into the equation of the parabola for $k$ gives:

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$k = \\dfrac{y}{x^2} = \\dfrac{\\var{A[1]}}{\\var{A[0]}^2} = \\var{sigformat(k,3)}$.

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The value of $k$ for a parabola passing through the point $(\\var{b}, \\var{h})$ is determined the same way, and the resulting equation for the parabola is

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$y= \\dfrac{\\var{h}}{\\var{b}^2}\\;  x^2$

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Use the slider to find the approximate value of $k$ ($\\pm 0.1$) required so that the parabola passes through the indicated point.  (You may use the arrow keys for finer adjustment of the slider.)

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$k_{est} = $ [[0]] 

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Now substitute the coordinates of the known point into the equation of the parabola and solve for the exact value of $k$ to three significant figures.

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$k =$ [[1]]

Determine the equation for a parabola with a vertex at the origin, which passes through a known point located at $(\\var{b}, \\var{h})$.

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$y =$ [[2]]

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