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The first term of an AP is 5.The last term is 45 and the sum is 400 find the number of terms of the common difference |
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Answer» Answer: 8/3 Step-by-step explanation: In an AP, First term (a) = 5 Last term (L) = 45 Sum of the TERMS of the AP (Sn) = 400 Number of terms = (N) = ? Common difference = (d) = ? Now, Sn = n/2 × (a + l) => 400 = n/2 × (5 + 45) => n/2 × 50 = 400 => n = (400 × 2)/50 => n = 16 Again, l = a + (n - 1)d => 45 = 5 + (16 - 1) × d => 45 - 5 = 15d => d = 40/15 = 8/3 |
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