展开-cb^{5/2}(-(e^{-r/a}r^2)/a+2e^{-r/a}r)

解答

展开

- c b^{\frac{5}{2}} (- \frac{e ^{- \frac{r}{a}} r ^{2}}{a} + 2 e^{- \frac{r}{a}} r)

\frac{c e ^{- \frac{r}{a}} b ^{\frac{5}{2}} r ^{2}}{a} - 2 c e^{- \frac{r}{a}} b^{\frac{5}{2}} r

求解步骤

- c b^{\frac{5}{2}} (- \frac{e ^{- \frac{r}{a}} r ^{2}}{a} + 2 e^{- \frac{r}{a}} r)

使用分配律:

a (b + c) = ab + a c

a = - c b^{\frac{5}{2}}, b = - \frac{e ^{- \frac{r}{a}} r ^{2}}{a}, c = 2 e^{- \frac{r}{a}} r

= - c b^{\frac{5}{2}} (- \frac{e ^{- \frac{r}{a}} r ^{2}}{a}) + (- c b^{\frac{5}{2}}) \cdot 2 e^{- \frac{r}{a}} r

使用加减运算法则

- (- a) = a, + (- a) = - a

= c b^{\frac{5}{2}} \frac{e ^{- \frac{r}{a}} r ^{2}}{a} - 2 c e^{- \frac{r}{a}} b^{\frac{5}{2}} r

乘

c b^{\frac{5}{2}} \frac{e ^{- \frac{r}{a}} r ^{2}}{a} : \frac{c e ^{- \frac{r}{a}} b ^{\frac{5}{2}} r ^{2}}{a}

= \frac{c e ^{- \frac{r}{a}} b ^{\frac{5}{2}} r ^{2}}{a} - 2 c e^{- \frac{r}{a}} b^{\frac{5}{2}} r

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