Emma throws an object upward from a hill that is 64 feet high. the object has an initial velocity of 48 feet per second. the function y = -16x2 + 48x + 64 represents the height of the object, y, in terms of the time elapsed after the object is thrown, x. which statements about this function are true? the function is a linear function. the function is a nonlinear function. the function has a constant rate of change. the function does not have a constant rate of change. the function is a decreasing function.