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

解

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

ln ∣ x ∣ + \frac{1}{2} ln x^{2} + 4 - \frac{1}{2} arctan (\frac{x}{2}) + C

解答ステップ

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

以下の部分分数を得る:

\frac{2 x ^{2} - x + 4}{x ( x ^{2} + 4 )} : \frac{1}{x} + \frac{x - 1}{x ^{2} + 4}

= \int \frac{1}{x} + \frac{x - 1}{x ^{2} + 4} 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

= \int \frac{1}{x} d x + \int \frac{x - 1}{x ^{2} + 4} d x

\int \frac{1}{x} d x = ln ∣ x ∣

\int \frac{x - 1}{x ^{2} + 4} d x = \frac{1}{2} ln x^{2} + 4 - \frac{1}{2} arctan (\frac{x}{2})

= ln ∣ x ∣ + \frac{1}{2} ln x^{2} + 4 - \frac{1}{2} arctan (\frac{x}{2})

定数を解答に追加する

= ln ∣ x ∣ + \frac{1}{2} ln x^{2} + 4 - \frac{1}{2} arctan (\frac{x}{2}) + C