Un=∑k=0n(k2+1)−∑k=0n−1(k2+1)U_n = \sum_{k=0}^n (k^2 + 1) - \sum_{k=0}^{n-1} (k^2 + 1)Un=∑k=0n(k2+1)−∑k=0n−1(k2+1) where n n\,n is a positive integer.
Find U3 U_3\,U3 and U8U_8U8.
Solve Un=730U_n = 730Un=730.
178 exam-style questions on Edexcel A Level Maths Sequences and Series, covering 3.1 Arithmetic Sequences, 3.2 Arithmetic Series, 3.3 Geometric Sequences, 3.4 Geometric Series, 3.5 Sum to Infinity, 3.6 Sigma Notation, 3.7 Recurrence Relations, and 3.8 Modelling with Series. Each one has a worked solution and a mark scheme showing where the marks go.