The circumference of a coin is about 80mm what is the area

If x=-3 is the only x-intercept of the graph of a quadratic equation, which statement best discribes the discriminant of the equation?

If f(x) = x+8 and g(x) = 4x- 3, find (f+g)(x)

I’m on question 7 it says a covered water tank is in the shape of a cylinder the tank has a 28 inch diameter and a height of 66 inches to the nearest square inch what is the surface area of the water tank