Proof: [ let a > 0....so -a < 0 ....and let 2n + 1 be some odd integer]
(-a)2n + 1 =
(-a)2n * (-a) =
(-1 * a)2n * (-1 * a) =
(-1)2n * (a)2n * (-1)* (a) =
(-12)n * (a2)n * (-a) =
(1)n * (a2)n * (-a) = [1 raised to any power = 1....so we can ignore this term ]
(a2)n * (-a) .... and a2 for any "a" not equal to 0 is always positive....and a positive raised to any power "n" is also positive....so....the first term is always positive....and since -a < 0, the entire expression is < 0