



 
Hi Adiba, Did you draw a diagram? If the parabola is $y = f(x)$ then you are correct that with the axes as in my diagram $f(0) = 0.$ but also $f(100) = 0$ so $0$ and $100$ are roots of $f(x).$ Since it is a parabola (quadratic) these are the only roots so $f(x) = k x(x  100)$ for some constant $k.$ The maximum height of 40 meters occurs when $x = 50$ meters. What is $k?$ Penny  


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