展开 ((x-3)*(x+4))/(x^2)

解答

展开

\frac{( x - 3 ) \cdot ( x + 4 )}{x ^{2}}

1 + \frac{1}{x} - \frac{12}{x ^{2}}

求解步骤

\frac{( x - 3 ) ( x + 4 )}{x ^{2}}

乘开

(x - 3) (x + 4) : x^{2} + x - 12

= \frac{x ^{2} + x - 12}{x ^{2}}

使用分式法则:

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

\frac{x ^{2} + x - 12}{x ^{2}} = \frac{x ^{2}}{x ^{2}} + \frac{x}{x ^{2}} - \frac{12}{x ^{2}}

= \frac{x ^{2}}{x ^{2}} + \frac{x}{x ^{2}} - \frac{12}{x ^{2}}

使用法则

\frac{a}{a} = 1

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

= 1 + \frac{x}{x ^{2}} - \frac{12}{x ^{2}}

消掉

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

= 1 + \frac{1}{x} - \frac{12}{x ^{2}}

e x p an d (2 x + y) d x + (3 - 3 y) d y

e x p an d 24 ((n + 1)!)^{3} (3 n)!

e x p an d 1 - [x + 1]^{2}

e x p an d (2 e^{3 x} - e^{- 3 x})^{2}

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