\[w_{1}(z)=F\left({a,b\atop c};z\right)=(1-z)^{c-a-b}F\left({c-a,c-b\atop c};z%
\right)=(1-z)^{-a}F\left({a,c-b\atop c};\frac{z}{z-1}\right)=(1-z)^{-b}F\left(%
{c-a,b\atop c};\frac{z}{z-1}\right).\]