Lim (x->0) (sin7x +sin3x)/x sinx
Получим неопределенность 0/0 Правило Лопиталя lim x-> 0 (sin7x +sin3x) ' / (x sinx) ' = = lim x-> 0 (7cos7x + 3cos3x) / (sinx + x*cosx ) = = (7cos7*0 + 3cos3*0) / (sin0 + 0*cos0 ) = 10/0 = ∞