展开 ((2-3s)(s-1))/(s^3)

解答

展开

\frac{( 2 - 3 s ) ( s - 1 )}{s ^{3}}

- \frac{3}{s} + \frac{5}{s ^{2}} - \frac{2}{s ^{3}}

求解步骤

\frac{( 2 - 3 s ) ( s - 1 )}{s ^{3}}

乘开

(2 - 3 s) (s - 1) : - 3 s^{2} + 5 s - 2

= \frac{- 3 s ^{2} + 5 s - 2}{s ^{3}}

使用分式法则:

\frac{a \pm b}{c} = \frac{a}{c} \pm \frac{b}{c}

\frac{- 3 s ^{2} + 5 s - 2}{s ^{3}} = - \frac{3 s ^{2}}{s ^{3}} + \frac{5 s}{s ^{3}} - \frac{2}{s ^{3}}

= - \frac{3 s ^{2}}{s ^{3}} + \frac{5 s}{s ^{3}} - \frac{2}{s ^{3}}

消掉

\frac{3 s ^{2}}{s ^{3}} : \frac{3}{s}

= - \frac{3}{s} + \frac{5 s}{s ^{3}} - \frac{2}{s ^{3}}

消掉

\frac{5 s}{s ^{3}} : \frac{5}{s ^{2}}

= - \frac{3}{s} + \frac{5}{s ^{2}} - \frac{2}{s ^{3}}

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