\[y(x)=\sum_{n=1}^{\infty} \dfrac{\left(f, \phi_{n}\right)}{-N_{n} \lambda_{n}} \phi_{n}(x)=\int_{a}^{b} \underbrace{\sum_{n=1}^{\infty} \dfrac{\phi_{n}(x) \phi_{n}(\xi)}{-N_{n} \lambda_{n}}}_{G(x, \x...y(x)=∞∑n=1(f,ϕn)−Nnλnϕn(x)=∫ba∞∑n=1ϕn(x)ϕn(ξ)−Nnλn⏟G(x,ξ)f(ξ)dξ &=\ dfrac {\ izquierda (1-2\ sin ^ {2} x\ derecha)\ sin 1\ cos 1-\ sin x\ cos x\ izquierda (2\ cos ^ {2} 1-1\ derecha) -\ sin x\ cos x-\ sin 1\ cos 1} {8\ sin 1\ cos 1} +\ dfrac {x^ {2}} {4}\\
