General method: ① If all denominators are monomials, then the simplest common denominator is the least common multiple of all coefficients, the highest power of the same letter, and all different letters are written as products.

(2) If all denominators are polynomials, you can factorize all denominators, take the least common multiple of the digital coefficients of all denominators, and take the highest power as the power of the base whenever letters (or algebraic expressions with letters) appear.