1.
Let f:RRf: \mathbb{R} \to \mathbb{R} be a real valued function such that f(10+x)=f(10x)f(10+x) = f(10-x) xR\forall x \in \mathbb{R} and f(20+x)=f(20x)f(20+x) = -f(20-x) xR\forall x \in \mathbb{R}. Then which of the following statements is true?