To find the value of $(f \circ g)'$ at $x = 49$, we need to apply the chain rule, which states:

$(f \circ g)'(x) = f'(g(x)) \cdot g'(x)$

Steps:

1. Define the functions:
   • $f(u) = \frac{u-1}{u+1}$
   • $g(x)$ is missing in the problem. To proceed, I will need the explicit form of $g(x)$.

Can you please provide the function $g(x)$?