Question

Интеграл
x2 -6x+8/x3+8 dx
Помогите пожалуйста

Answer 1

$\int\frac{x^2-6x+8}{x^3+8x}dx=\int\frac{(x^2+8)-6x}{x(x^2+8)}dx=\int\left(\frac{(x^2+8)}{x(x^2+8)}-\frac{6x}{x(x^2+8)}\right)dx=\\\\=\int\left(\frac1x-\frac6{x^2+8}\right)dx=\int\frac{dx}x-6\int\frac{dx}{x^2+8}=\ln x-6\cdot\frac1{\sqrt8}\cdot arctg\left(\frac x{\sqrt8}\right)+C=\\\\=\ln x-6\cdot\frac1{2\sqrt2}\cdot arctg\left(\frac x{2\sqrt2}\right)+C=\ln x-\frac3{\sqrt2}\cdot arctg\left(\frac x{2\sqrt2}\right)+C$