Un elev are un numar de fotografii cu diverse specii de animale si pasari. vrand sa le lipeasca pe filele unui album, consta ca daca le aseaza cite 3 sau cite 4, sau cite 5, sau cite 6 pe ultima fila ii ramine de fiecare data o fotografie. daca le asezam cite 7 pe fiecare fila, atunci nu-i va ramine niciuna. cite foografii are elevul?

Amass weighing 16 pounds stretches a spring 8/3 feet. the mass is initially released from rest from a point 2 feet below the equilibrium position, and the subsequent motion takes place in a medium that offers a damping force that is numerically equal to 1/2 the instantaneous velocity. find the equation of motion if the mass is driven by an external force equal to f(t)=cos(2t).