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InterviewSolution
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In an A.P., the first term is 2, the last term is 29 and the sum of the terms is 155. Find the common difference of the A.P. |
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Answer» Given, First term, a = 2 Last term, an = l = 29 And, Sum of terms, Sn = \(\frac{n}{2}\)[a + l] 155 = \(\frac{n}{2}\)[ 2 + 29] 155 x 2 = n x 31 n = \(\frac{155 \times 2}{31}\) = \(\frac{310}{31} = 10\) We know, an = a + (n - 1)d 29 = 2 = (10 - 1)d 29 - 2 = 9d 27 = 9d d = 3 Hence, common difference, d = 3 sum of an AP: n/2(a+an) (a:first term,an:last term)given: s=155 a=2 an=29 n=? d=? :155=n/2(2+29) n=10 therefore, an=a+(n-1)d (where n is the total no of terms in ap) 29=2+(10-1)d hence ,common difference,d=3 |
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