Calculezi F'(x), sau integrala din f(x).
F'(x) = (x^2+x+lnx)'= 2x+1+1/x = f(x)
[tex] \int\limits f(x)dx = \int\limits( 2x+1+1/x) dx=\int\limits 2x dx+ \int\limits 1dx + \int\limits \frac{1}{x}dx = \\ = 2*\frac{x^{2} }{2}+x+lnx + C= x^{2} +x+lnx + C = F(x)[/tex]
=> F(x) primitiva functiei f(x)