展开 (r(2+r))/2

解答

展开

\frac{r ( 2 + r )}{2}

\frac{r ^{2}}{2} + r

求解步骤

\frac{r ( 2 + r )}{2}

乘开

r (2 + r) : 2 r + r^{2}

= \frac{2 r + r ^{2}}{2}

使用分式法则:

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

\frac{2 r + r ^{2}}{2} = \frac{2 r}{2} + \frac{r ^{2}}{2}

= \frac{2 r}{2} + \frac{r ^{2}}{2}

数字相除:

\frac{2}{2} = 1

= r + \frac{r ^{2}}{2}

改写为标准形式

= \frac{r ^{2}}{2} + r

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

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

s im pl i f y (1 + i)^{19}

e x p an d \frac{( n + 1 ) ^{2} sin ( \frac{1}{n + 1} )}{n ^{2} sin ( \frac{1}{n} )}

e x p an d \frac{6 x + 5}{( 2 x - 1 ) ^{2}}