We study short sums of algebraic trace functions via the q-analogue of van der Corput method, and develop methods of arithmetic exponent pairs that coincide with the classical case while the moduli has sufficiently good factorizations. As an application, we prove a quadratic analogue of Brun-Titchmarsh theorem on average, bounding the number of primes p X with p 2 + 1 ≡ 0 (mod q). The other two applications include a larger level of distribution of divisor functions in arithmetic progressions and a sub-Weyl subconvex bound of Dirichlet L-functions studied previously by Irving. Contents 14 4. Producing new exponent pairs: the first approach 19 5. Proof of Theorems 4.1, 4.2 and 4.3 21 6. Producing new exponent pairs: the second approach 26 7. Arithmetic exponent pairs with constraints 29 8. Explicit estimates for sums of trace functions 30 9. Proof of Theorem 1.1: Quadratic Brun-Titchmarsh theorem 31 10. Proof of Theorems 1.2 and 1.3: Divisor functions in arithmetic progressions and subconvexity of Dirichlet L-functions 40 Appendix A. Several lemmas 41 Appendix B. Estimates for complete exponential sums 43 References 45