Question
The fourth term of an arithmetic progression is 6. Then
the sum of first seven terms is:Solution
Given, a + 3d = 6 Accoding to the question Sum of first seven term a + a + d + a + 2d + a + 3d + a + 4d + a + 5d + a + 6d ⇒ 7a + 21d ⇒ 7 (a + 3d) ⇒ 7 × 6 ⇒ 42
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