Chapter 5: Arithmetic Progressions

Example 6. Find the sum of first 30 terms of an A. P. whose nth term is 2 + 1/2n

Solution:-

tn = 2 + 1/2n

tn - 1 = 2 + 1/2( n- 1)

tn - tn - 1 = 2 + 1/2n - 2 - 1/2(n - 1)

d = 1/2

a = t1 = 2 + 1/2 X 1 = 5/2

n = 30

 

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Subjects Maths (Part-1) by Mr. M. P. Keshari
Chapter 1 Linear Equations in Two Variables
Chapter 2 HCF and LCM
Chapter 3 Rational Expression
Chapter 4 Quadratic Equations
Chapter 5 Arithmetic Progressions
Chapter 6 Instalments
Chapter 7 Income Tax
Chapter 8 Similar Triangles