integral of (2x)/((x-4)(x+3))

解

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

2 (\frac{4}{7} ln ∣ x - 4 ∣ + \frac{3}{7} ln ∣ x + 3 ∣) + C

解答ステップ

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

定数を除く:

\int a \cdot f (x) d x = a \cdot \int f (x) d x

= 2 \cdot \int \frac{x}{( x - 4 ) ( x + 3 )} d x

以下の部分分数を得る:

\frac{x}{( x - 4 ) ( x + 3 )} : \frac{4}{7 ( x - 4 )} + \frac{3}{7 ( x + 3 )}

= 2 \cdot \int \frac{4}{7 ( x - 4 )} + \frac{3}{7 ( x + 3 )} d x

総和規則を適用する:

\int f (x) \pm g (x) d x = \int f (x) d x \pm \int g (x) d x

= 2 (\int \frac{4}{7 ( x - 4 )} d x + \int \frac{3}{7 ( x + 3 )} d x)

\int \frac{4}{7 ( x - 4 )} d x = \frac{4}{7} ln ∣ x - 4 ∣

\int \frac{3}{7 ( x + 3 )} d x = \frac{3}{7} ln ∣ x + 3 ∣

= 2 (\frac{4}{7} ln ∣ x - 4 ∣ + \frac{3}{7} ln ∣ x + 3 ∣)

定数を解答に追加する

= 2 (\frac{4}{7} ln ∣ x - 4 ∣ + \frac{3}{7} ln ∣ x + 3 ∣) + C