If f (x) is defined as a function on R, and f (10 + x) = f (10-x), f (20-x) = - f (20 + x), it is proved that f (x) is an odd function and periodic function

If f (x) is defined as a function on R, and f (10 + x) = f (10-x), f (20-x) = - f (20 + x), it is proved that f (x) is an odd function and periodic function

F (x) = f (10 + (X-10)) = f (10 - (X-10)) = f (20-x) = - f (20 + x) = - f (10 + (10 + x)) = - f (10 - (10 + x)) = - f (- x) is an odd function
Then the basis function is randomly brought into a formula to see that it is a periodic function