CBSE NCERT Solutions Chapter 5 Arithmetic Progressions Exercise 5.3 Question 7
7. Find the sum of first 22 terms of an AP in which d = 7 and 22nd term is 149.
Solution:
It is given that 22nd term is equal to 149.
It means
Using formula
, to find nth term of arithmetic progression, we can say that
Applying formula,
to find sum of n terms of AP and putting value of a, we get
Therefore, sum of first 22 terms of AP is equal to
.
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