NCERT MATHS CLASS - X
Arithmetic Progressions
Exercise 5.3
Question 1:
Find the sum of the following APs.
(i) 2, 7, 12 ,…., to 10 terms.
(ii) − 37, − 33, − 29 ,…, to 12 terms
(iii) 0.6, 1.7, 2.8 ,…….., to 100 terms
Sol.
Given
a = 2, d = a2 − a1 = 7 − 2 = 5, n = 10
The sum of nth terms of an AP is given by
(ii)−37, −33, −29,…, to 12 terms
Given
a = −37, d = a2 − a1 = (−33) − (−37)
= − 33 + 37 = 4
n = 12
The sum of nth terms of an AP is given by
(iii) 0.6, 1.7, 2.8 ,…, to 100 terms
Given
a = 0.6, d = a2 − a1 = 1.7 − 0.6 = 1.1, n = 100
The sum of nth terms of an AP is given by
Given
n = 11
The sum of nth terms of an AP is given by
