Hi can someone plss help me with this!!

What is the missing constant term in the perfect square that starts with x^2 -20x

An architect is designing a water fountain for a park she uses the given function to model the water jet flowing from the fountain nozzles where h(x) gives the height of the water jugs in feet x feet from the starting point h(x)=-1/20x+x+15

Which of the following three dimensional figures has a circle as it’s base