展开 (2(n-2E)^2)/(n^2)

解答

展开

\frac{2 ( n - 2 E ) ^{2}}{n ^{2}}

2 - \frac{8 E}{n} + \frac{8 E ^{2}}{n ^{2}}

求解步骤

\frac{2 ( n - 2 E ) ^{2}}{n ^{2}}

(n - 2 E)^{2} = n^{2} - 4 n E + 4 E^{2}

= \frac{2 ( 4 E ^{2} - 4 n E + n ^{2} )}{n ^{2}}

乘开

2 (n^{2} - 4 n E + 4 E^{2}) : 2 n^{2} - 8 n E + 8 E^{2}

= \frac{2 n ^{2} - 8 n E + 8 E ^{2}}{n ^{2}}

使用分式法则:

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

\frac{2 n ^{2} - 8 n E + 8 E ^{2}}{n ^{2}} = \frac{2 n ^{2}}{n ^{2}} - \frac{8 n E}{n ^{2}} + \frac{8 E ^{2}}{n ^{2}}

= \frac{2 n ^{2}}{n ^{2}} - \frac{8 n E}{n ^{2}} + \frac{8 E ^{2}}{n ^{2}}

消掉

\frac{2 n ^{2}}{n ^{2}} : 2

= 2 - \frac{8 n E}{n ^{2}} + \frac{8 E ^{2}}{n ^{2}}

消掉

\frac{8 n E}{n ^{2}} : \frac{8 E}{n}

= 2 - \frac{8 E}{n} + \frac{8 E ^{2}}{n ^{2}}

e x p an d (2 x y^{2} + \frac{x}{y ^{2}}) d x

e x p an d a^{a^{a} (a + 1)}

e x p an d \frac{( 2 - 1 ) 486 π}{5}

e x p an d \frac{2 ( x ^{4} + 18 )}{x ^{4}}

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