# Where did the cosines come from?

**Calculus**Level 2

Let \( \sum\limits_{n=0}^\infty a_n \) and \( \sum\limits_{n=0}^\infty b_n \) be two convergent numerical series with positive terms.

**True or false?**:

The series \( \sum\limits_{n=0}^\infty \left(a_n\cos(b_nx)+b_n\sin(a_nx) \right) \) is convergent in \(\mathbb{R} \).