If $\;f(x) = x^{2}-x+5\;,x > \large\frac{1}{2}\;$ , and $\;g(x)\;$ is its inverse function , then $\;g^{'}(7)\;$ equals :

Question

$(a)\;- \large\frac{1}{3} \qquad(b)\; \large\frac{1}{13} \qquad(c)\; \large\frac{1}{3} \qquad(d)\;- \large\frac{1}{13} $