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In an AP, if the common difference (d) = – 4, and the seventh term (a7) is 4, then find the first term. |
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Answer» a + 6 (–4) = 4 ⇒ a = 28 Detailed Answer : Given d = – 4 and a7 = 4 We know that nth term of A.P. is an = a + (n – 1)d a7 = a + (7 – 1)d [n = 7] 4 = a + 6(– 4) ∴ a = 4 + 24 = 28 ∴ First term of an A.P. = 28. n th term an = a1+ (n-1)d a7 = a1+( 7-1)* (-4) => 4 = a1+( 7-1)* (-4) => a1= 4-+24 =28 |
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