Remember that
The odd functions are functions that return their negative inverse when x is replaced with –x. This means that f(x) is an odd function when f(-x) = -f(x)
Verify
For x=3
f(3)=-7
f(-3)=-7
therefore
f(-x) is not equal to -f(x)
the function is not odd
Even function
A function is an even function if f of x is equal to f of −x for all the values of x
so
f(x)=f(-x)
we have that
f(3)=-7
f(-3)=-7
so
f(x)=f(-x)
therefore
Is an even function
