How would I show that

(cond f X g)(x) <= (cond f)(x) + (cond g)(x)

am I right to assume that (cond f)(x)= (X x f(prime)(X))/f(X)

Also how would I analyze the error propagation in the exponent x^a (x>0)

1. x is exact and a is subject to a small error

2. a is exact and x is subject to small error

Thank you