(−1)rrrr(-1)^{r} r r^{r}(−1)rrrr
(r+1)xr+1(r+1) x^{r+1}(r+1)xr+1
(r+1)xr(r+1) x^{r}(r+1)xr
(−1)r(r+1)xr(-1)^{r}(r+1) x^{r}(−1)r(r+1)xr