15: D( f ) = (−∞,0) ∪ (0,∞); f is continuous there.
y-intercept: f (0) not possible; x-intercepts: f = 0 gives x = 1. f is not symmetric, see f = 0. Limits at endpoints:
Interpretation as asymptotes: Horizontal asymptote y = −π/4 at −∞. Not a vertical asymptote at x = 0. Horizontal asymptote y = π/4 at ∞.
Now determine monotonicity using f ′.
Next hint Answer