展开 (r^{k-1}(r^2-r^3-1)+1)/(1-r)

解答

展开

\frac{r ^{k - 1} ( r ^{2} - r ^{3} - 1 ) + 1}{1 - r}

\frac{r ^{k + 1} - r ^{k + 2} - r ^{k - 1} + 1}{1 - r}

求解步骤

\frac{r ^{k - 1} ( r ^{2} - r ^{3} - 1 ) + 1}{1 - r}

乘开

r^{k - 1} (r^{2} - r^{3} - 1) + 1 : r^{k + 1} - r^{k + 2} - r^{k - 1} + 1

= \frac{r ^{k + 1} - r ^{k + 2} - r ^{k - 1} + 1}{1 - r}

e x p an d \frac{- 1}{3} (x^{2} + 2 (- 5) x + (- 5)^{2} + (- 4) = 0)

e x p an d \frac{2 ( 2 5 - 2 2 )}{3}

e x p an d ((n + 1)! (n + 2)) - 1

e x p an d (y - x) d x + (y + x) d y

e x p an d ((x + 1) - (e^{8 x - 8}))^{2}