sorry for the so simple description
this is a expand F(x) with particle in a box energy eigenfuctions
F(x)=x(x-l) for 0<x<l and F(x)=0 elsewhere
psi is the wave function of ground state particle in a box equation
So at the core you need $$ \int_0^l x\, sin(ax)\; dx {\rm \quad and \quad} \int_0^l x^2 \,sin(ax)\; dx$$ (with ## a = n\pi/l##) , right ?
Ever met these integrals ?
So at the core you need $$ \int_0^l x\, sin(ax)\; dx {\rm \quad and \quad} \int_0^l x^2 \,sin(ax)\; dx$$ (with ## a = n\pi/l##) , right ?
Ever met these integrals ?