f(x)=loga(a-a*x)=loga[a(1-x)]=logaa+loga(1-x)=1+loga(1-x)
1-x>0
∴xx2
f(x1)-f(x2)=loga(1-x1)-loga(1-x2)=loga[(1-x1)/(1-x2)]
x1>x2
∴1-x1
f(x)=loga(a-a*x)=loga[a(1-x)]=logaa+loga(1-x)=1+loga(1-x)
1-x>0
∴xx2
f(x1)-f(x2)=loga(1-x1)-loga(1-x2)=loga[(1-x1)/(1-x2)]
x1>x2
∴1-x1