Lời giải:
Ta có:
\(P=\int \frac{x^2}{2(x+2)}dx=\frac{1}{2}\int \frac{x^2}{x+2}dx=\frac{1}{2}\int \frac{x^2-4+4}{x+2}dx\)
\(=\frac{1}{2}\int \left(x-2+\frac{4}{x+2}\right)dx=\frac{1}{2}\int (x-2)dx+\int \frac{2}{x+2}dx\)
\(=\frac{1}{2}\int (x-2)dx+\int \frac{2d(x+2)}{x+2}\)
\(=\frac{1}{2}(\frac{x^2}{2}-2x)+2\ln |x+2|+c\)
\(=\frac{x^2}{4}-x+2\ln |x+2|+c\)