展开 ((x-2)(x+1))/2

解答

展开

\frac{( x - 2 ) ( x + 1 )}{2}

\frac{x ^{2}}{2} - \frac{x}{2} - 1

求解步骤

\frac{( x - 2 ) ( x + 1 )}{2}

乘开

(x - 2) (x + 1) : x^{2} - x - 2

= \frac{x ^{2} - x - 2}{2}

使用分式法则:

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

\frac{x ^{2} - x - 2}{2} = \frac{x ^{2}}{2} - \frac{x}{2} - \frac{2}{2}

= \frac{x ^{2}}{2} - \frac{x}{2} - \frac{2}{2}

使用法则

\frac{a}{a} = 1

\frac{2}{2} = 1

= \frac{x ^{2}}{2} - \frac{x}{2} - 1

e x p an d l (e^{t} + 1) h (t - 2)

e x p an d (\frac{π}{2} + 2) r

e x p an d 2 π (81 h - h^{3})

e x p an d x (1 + 23) - 3 - 63

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