Is this alternative odd function equation valid? An odd function is a function where: 
$$f(-x) = -f(x)$$
Is this alternative form valid ? 
$$f(x) = -f(-x)$$ 
I'm asking because an odd function graphically is symmetrical with respects to the origin. 
Which means that the x and y point's signs are flipped. 
The second form seems easier to read (assuming it's valid).

(CW; just ensuring this question registers as answered.)
Yes: As remarked in the comments, the two equations are equivalent. This can be seen by simply multiplying both sides of one equation by $-1$ to obtain the other equation.
As to which one "seems easier to read," this is -- of course -- a matter of taste.
