Checkpoint 4 Answer

For positive values of `x`, it is clear that the signs alternate because of the factor `text[(]-1text[)]^k`. For negative values of `x`,

`x^(2k+1)=(-|x|)^(2k+1)=text[(]-1text[)]^(2k+1)|x|^(2k+1)`,

which is always negative. Thus the sign is always opposite to that of `text[(]-1text[)]^k` and again the signs alternate.