If f(x) = (x − 1)/(x + 1) and g(x) = (x + 1)/(x − 1), what is the value of (f + g)(0)?

Correct answer: −2

Answer: A, −2. To evaluate (f+g)(0), first confirm that both functions are defined at x=0. For f, the denominator is 0+1=1; for g, it is 0−1=−1. Neither is zero, so direct substitution is allowed. Now f(0)=(0−1)/(0+1)=−1 and g(0)=(0+1)/(0−1)=−1. Therefore (f+g)(0)=−1+(−1)=−2. Option A is correct. B would incorrectly treat the two values as cancelling. C has the wrong sign or arithmetic. D is not correct because undefinedness occurs only when a denominator is zero: f excludes x=−1 and g excludes x=1, not x=0. The safe procedure for rational functions is: check denominators first, substitute second, and add in the stated order.