19: D( f ) = (−1,1) ∪ (1,∞); f is continuous there.
y-intercept: f (0) = 0; x-intercepts: f = 0 gives x = 0. f is not symmetric since D( f ) is not symmetric. Limits at endpoints:
Interpretation as asymptotes: Vertical asymptote at x = −1. Vertical asymptote at x = 1. Horizontal asymptote y = 0 at ∞.
Now determine monotonicity using f ′.
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