Past exam of the mathematics course of the University of Cambridge 2023 ii Paper 2 32E b Solution Created 2026-09-24 Updated 2026-10-03
Take . It has the exact expansionSuppose it had an expansion . The order-zero condition forces . At order one we would then require some constant such thatAfter division by , the left side is , which cannot tend to zero. This contradiction proves that no such coefficients exist. Thus termwise equivalent asymptotic scales need not preserve expansions.