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

1.	Given l = 28, S = 144, and there are total 9 terms. Find a.
Answer» Given: l = a₉ = a + 8d = 28 and S₉ = 144 But, Now, S_n = \(\frac{n}{2}\)(a + l) 144 = \(\frac{9}{2}\)(a + 28) ⇒ 144 × \(\frac{2}{9}\) = a + 28 ⇒ a + 28 = 32 ⇒ a = 4

Answer»

Given:

l = a₉ = a + 8d = 28 and S₉ = 144 But,

Now, S_n = \(\frac{n}{2}\)(a + l)

144 = \(\frac{9}{2}\)(a + 28)

⇒ 144 × \(\frac{2}{9}\) = a + 28

⇒ a + 28 = 32

⇒ a = 4

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