I'm taking a statistics course and reading notes this equation :
$$ \frac{1-n}{2}(1-2t)^{\frac{1-n}{2}}(-2) $$
is simplified to :
$$ (n-1)(1-2t)^{\frac{-1-n}{2}} $$
Simplification I've calculated is result of multiplying
$$ \frac{1-n}{2}(1-2t)^{\frac{1-n}{2}} $$
by -2 :
$$ \frac{1-n}{2}(2+4t)^{\frac{1-n}{2}} $$
How is more simpler version :
$$ (n-1)(1-2t)^{\frac{-1-n}{2}} $$
arrived at ?
Just: $$\frac{1-n}{2}(1-2t)^{\frac{1-n}{2}}(-2)=\left((-2)\cdot\frac{1-n}{2}\right)(1-2t)^{\frac{1-n}{2}}=(n-1)(1-2t)^{\frac{1-n}{2}}.$$