A sequence u1,u2,u3,… u_1, u_2, u_3, \dots\,u1,u2,u3,… is defined by
u4=13,u5=21un=un−1+un−2,n≥3 \begin{aligned}u_4 &= 13, u_5 = 21 \\u_n &= u_{n-1} + u_{n-2}, \quad n \geq 3\end{aligned} u4un=13,u5=21=un−1+un−2,n≥3Find u1,u2 u_1, u_2\,u1,u2 and u3u_3u3.
326 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.