Given the function f(x) = x^2 and k= -1, which of the following represents a function opening downward?

Question

A:f(x)+k

b: kf(x)

c: f(x+k)

d: f(kx)

 

Answer 1

b because all of the y values from f(x) = x² are multiplied by -1 to get the new function, which has y values all negative where they were formerly positive. (The vertex of each remains the origin.)