# In an Ap: Given L = 28, S = 144, and There Are Total 9 Terms. Find a - Mathematics

In an AP:

Given l = 28, S = 144, and there are total 9 terms. Find a.

#### Solution

Given that, l = 28, S = 144 and there are total of 9 terms.

S_n = n/2(a+1)

144 = 9/2(a+28)

(16) × (2) = a + 28

32 = a + 28

a = 4

Concept: Sum of First n Terms of an AP
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#### APPEARS IN

NCERT Class 10 Maths
Chapter 5 Arithmetic Progressions
Exercise 5.3 | Q 3.1 | Page 112

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