I am getting the following, using the property $\Gamma(z) = z\Gamma(z-1)$
$\frac{1}{2}\frac{\Gamma(\frac{v}{2}-1)}{\Gamma(\frac{v}{2})} = \frac{1}{2}\frac{\Gamma(\frac{v}{2}-1)}{\frac{v}{2}\times\Gamma(\frac{v}{2}-1)} = \frac{1}{v}$
But the answer is supposed to be $\frac{1}{v-2}$