Question 1119176
{{{y=a(x-60)^2+50}}}

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{{{a(x-60)^2=y-50}}}

{{{a=(y-50)/(x-60)^2}}}

{{{a=(0-50)/(120-60)^2}}}

{{{a=-50/3600}}}

{{{a=-1/72}}}

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{{{y=-(1/72)(x-60)^2}}}