how many terms of the A.P 7,14,21,,,are needed to give the sum 5740
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Answer:
Sn = n/2{2a + (n-1)d}
5740= n/2{ 14+(n-1)7}
5740= n/2{ 14 +7n-7}
5740=n/2(7-7n)
5740=7n/2-7n^2/2
11480=7n-7n^2
7n^2-7n+11480=0
n^2-n+1640=0
now solve the equation to get ur answer
Step-by-step explanation:
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