展开 ((x-3)(x+5))/2

解答

展开

\frac{( x - 3 ) ( x + 5 )}{2}

\frac{x ^{2}}{2} + x - \frac{15}{2}

求解步骤

\frac{( x - 3 ) ( x + 5 )}{2}

乘开

(x - 3) (x + 5) : x^{2} + 2 x - 15

= \frac{x ^{2} + 2 x - 15}{2}

使用分式法则:

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

\frac{x ^{2} + 2 x - 15}{2} = \frac{x ^{2}}{2} + \frac{2 x}{2} - \frac{15}{2}

= \frac{x ^{2}}{2} + \frac{2 x}{2} - \frac{15}{2}

数字相除:

\frac{2}{2} = 1

= \frac{x ^{2}}{2} + x - \frac{15}{2}

e x p an d (\frac{- 2 x + 5}{3})^{2}

e x p an d e^{3 t} (t + cos (t))^{2}

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

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

s im pl i f y (4 x + 3 y) (x - 3 y)