A. Yes, it's true that the domain is x is a real number.
B. No, the range of f is (-∞, 0].
C. No, f is only decreasing over the interval (0, ∞).
D. Yes, The point (0,0) is a maximum.
E. No, since (0,0) is already a maximum and it's a zero so there is only one x-intercept.