How to extend a given function to an odd function with period 2 (Fourier Series)

Question

This is the question.

f(x) = 7x^2 + 4

I want to know how to extend the above fuction to become a odd function with period 2.

Answer 1

$g(x) = f(x), 0\leq x\leq 1,$

$g(x) = -f(x), -1 \leq x \leq 0,$

$ g(x) = g(x+2)$ to define g(x) in x $\in \mathbb R$