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Sequences and Series

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Question 132
i.

The power output of a prototype micro-sensor, PnP_nPn​ (in microwatts), during its nnn-th hour of operation is modeled by the geometric sequence Pn=45(0.8)nP_n = 45(0.8)^nPn​=45(0.8)n for n∈Nn \in \mathbb{N}n∈N. Calculate the total energy ∑n=1∞Pn\sum_{n=1}^{\infty} P_n∑n=1∞​Pn​ consumed by the sensor if it operates indefinitely.

[2]
a.

A sequence of experimental index values v1,v2,v3,… v_1, v_2, v_3, \dots\,v1​,v2​,v3​,… is defined by the recurrence relation:

vn+1=11−vn,n∈N v_{n+1} = \frac{1}{1 - v_n}, \quad n \in \mathbb{N} vn+1​=1−vn​1​,n∈N

Given that the initial value is v1=23\displaystyle v_1 = \frac{2}{3}v1​=32​:

Show that this sequence is periodic.

[2]
b.

State the order of this sequence.

[1]
c.

Determine the sum of the first 100 terms of the sequence, ∑n=1100vn\sum_{n=1}^{100} v_n∑n=1100​vn​.

[3]

Sequences and Series Questions

  1. A Level
  2. /Maths
  3. /Sequences and Series

Practise Edexcel A Level Maths Sequences and Series with exam-style questions for A Level Maths. 156 questions 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, matched to the Edexcel A Level Maths (9MA0) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.

Question bank