Răspuns:
Explicație pas cu pas:
Acolo se face schimbarea de variabila g(x)=t.
[tex]g(x)=t\\g'(x)dx=dt\\f(x)dx=dt[/tex]
Integrala devine :
[tex]\displaystyle\int_{g(1)}^{g(e)}tdt=\dfrac{t^2}{2}|_{g(1)}^{g(e)}=\dfrac{1}{2}(g^2(e)-g^2(1))[/tex]
Daca era [tex]\dfrac{1}{2}\displaystyle\int F^2(x)\cdot F'(x)[/tex] , atunci da, integrala era intr-adevar F^3(x)/3
