A physics major should focus on a robust mathematical foundation, emphasizing calculus, differential equations, and linear algebra. Differential equations are particularly crucial for understanding physical systems, while linear algebra is essential for quantum mechanics and classical mechanics. Recommended textbooks include Boas' "Mathematical Methods in the Physical Sciences," Arfken's "Mathematical Physics," and Boyce and DiPrima for differential equations. Additional topics like complex analysis, group theory, and differential geometry are also beneficial, especially for those pursuing theoretical physics or specialized fields like condensed matter physics. The consensus is that a strong grasp of mathematics enhances comprehension and application in physics, making it advantageous to learn as much math as possible, even beyond what is strictly required.