Let g(x)=f(x)−1 . If f(x)+f(1−x)=2∀x∈R, then g(x) is symmetrical about
the origin
the line x=12
the point (1,0)
the point 12,0
f(x)−1+f(1−x)−1=0
So, g(x)+g(1−x)=0
Replacing x by x+12, we get g12+x+g12−x=0
So, it is symmetrical about 12,0 . If fa+x+fa-x=0 then fx is symmetric about a,0