If f(x+a)=f(x+b), the function changes periodically: the minimum positive period T= internal large variable minus internal small variable.

f(x+ 1)= f(x-2)= = & gt； T=3

f(x+ 1)=-f(x-2)，= =》T/2 = 3 = = & gt； T=6 (internal subtraction is constant)

f(x+ 1)= f(2-x)= & gt； The symmetry axis is: x=(x+ 1+2-x)/2=3/2 (the internal addition is unchanged).

F (x+ 1) =-f (2-x) The abscissa of the symmetry point is x=3/2, and the ordinate is equal to 0.