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Understanding Human Behaviour Without Spoken Words — Edwin Ogie Library Understanding Human Behaviour Without Spoken Words Nonverbal Communication as a core human skill — simple, practical, and classroom-friendly. Chapter Objectives Introduction Meaning & Scope Major Channels Interpreting Behaviour Culture & Ethics Practical Applications Case Illustrations Reflection & Practice Summary & Terms By Edwin Ogie Library — clear, usable lessons for students and teachers. Chapter Objectives At the end of this chapter, the reader should be able to: Clearly define nonverbal communication and explain its role in human interaction. Identify and interpret major forms of nonverbal behaviour with accuracy. Analyse behaviour using clusters of cues rather than isolated signals. Apply nonverbal awareness eff...

PROGRESSION

Lesson Note: Progressions (nth Term & Sum of A.P. and G.P.)

Progression: nth Term of a Progression

This lesson note explains how to determine the nth term in a progression. We consider both:

A. Arithmetic Progression (A.P.)

The nth term of an A.P. is given by:

an = a + (n - 1)d, where:

  • a is the first term,
  • d is the common difference, and
  • n is the term number.
  • Example 1: For a = 2 and d = 3, find the 5th term.
    a5 = 2 + (5 - 1)×3 = 2 + 12 = 14.
  • Example 2: For a = 7 and d = 2, find the 8th term.
    a8 = 7 + (8 - 1)×2 = 7 + 14 = 21.
  • Example 3: For a = 1 and d = 4, find the 6th term.
    a6 = 1 + (6 - 1)×4 = 1 + 20 = 21.
  • Example 4: For a = 10 and d = -2, find the 4th term.
    a4 = 10 + (4 - 1)×(-2) = 10 - 6 = 4.

B. Geometric Progression (G.P.)

The nth term of a G.P. is given by:

an = a × r(n - 1), where:

  • a is the first term,
  • r is the common ratio, and
  • n is the term number.
  • Example 1: For a = 2 and r = 2, find the 5th term.
    a5 = 2 × 2(5 - 1) = 2 × 16 = 32.
  • Example 2: For a = 3 and r = 3, find the 4th term.
    a4 = 3 × 3(4 - 1) = 3 × 27 = 81.
  • Example 3: For a = 5 and r = 0.5, find the 6th term.
    a6 = 5 × (0.5)(6 - 1) = 5 × 0.03125 ≈ 0.15625.
  • Example 4: For a = 10 and r = 0.8, find the 3rd term.
    a3 = 10 × (0.8)(3 - 1) = 10 × 0.64 = 6.4.

Progression: Sum of A.P. and G.P.

This section explains how to find the sum of the first n terms in both Arithmetic and Geometric progressions.

A. Sum of an Arithmetic Progression (A.P.)

The sum of the first n terms of an A.P. is given by:

Sn = n/2 [2a + (n - 1)d] or Sn = n/2 (first term + last term).

  • Example 1: For a = 2 and d = 3 (5 terms),
    S5 = 5/2 [2×2 + (5 - 1)×3] = 5/2 × 16 = 40.
  • Example 2: For a = 7 and d = 2 (8 terms),
    S8 = 8/2 [2×7 + (8 - 1)×2] = 4 × 28 = 112.
  • Example 3: For a = 1 and d = 4 (6 terms),
    S6 = 6/2 [2×1 + (6 - 1)×4] = 3 × 22 = 66.
  • Example 4: For a = 10 and d = -2 (4 terms),
    S4 = 4/2 [2×10 + (4 - 1)×(-2)] = 2 × 14 = 28.

B. Sum of a Geometric Progression (G.P.)

The sum of the first n terms of a G.P. (for r ≠ 1) is given by:

Sn = a (rn - 1) / (r - 1) (if r > 1) or Sn = a (1 - rn) / (1 - r) (if r < 1).

  • Example 1: For a = 2 and r = 2 (5 terms),
    S5 = 2 × (25 - 1)/(2 - 1) = 2 × 31 = 62.
  • Example 2: For a = 3 and r = 3 (4 terms),
    S4 = 3 × (34 - 1)/(3 - 1) = 3 × 40 = 120.
  • Example 3: For a = 5 and r = 0.5 (6 terms),
    S6 = 5 × (1 - 0.56)/(1 - 0.5) ≈ 9.84.
  • Example 4: For a = 10 and r = 0.8 (3 terms),
    S3 = 10 × (1 - 0.83)/(1 - 0.8) = 24.4.

Quiz on Progressions (Multiple Choice)

Total time: 300 seconds

This topic explains how to determine the nth term of a progression, including both arithmetic and geometric progressions. A.P. Example: a = 2, d = 3, n = 5, a5 = 2 + (5-1)*3 = 14. A.P. Example: a = 7, d = 2, n = 8, a8 = 7 + (8-1)*2 = 21. G.P. Example: a = 2, r = 2, n = 5, a5 = 2 × 2^(5-1) = 32. G.P. Example: a = 3, r = 3, n = 4, a4 = 3 × 3^(4-1) = 81. This topic explains how to calculate the sum of terms in arithmetic and geometric progressions. A.P. Example: a = 2, d = 3, n = 5, S5 = 5/2 [2×2 + (5-1)*3] = 40. A.P. Example: a = 7, d = 2, n = 8, S8 = 8/2 [2×7 + (8-1)*2] = 112. G.P. Example: a = 2, r = 2, n = 5, S5 = 2*(2^5-1)/(2-1) = 62. G.P. Example: a = 3, r = 3, n = 4, S4 = 3*(3^4-1)/(3-1) = 120.

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