find the number of terms in the series 20 + 58/3 + 56/3........... of which the sum is 300 and explain the double answer. i have got the ans. as n = 25 , 36 how to xplain the double ans.???? answer soon zz
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it is an A.P with common difference 2/3
so using formula of sum of n terms
(n/2)(2a+(n-1)d) we get a quadratic equation which will have 2 answers
the reason for 2 answers is after some amount of terms negative terms will start coming so the total sum of n terms will go back the way it started,
for example in the A.p 3,2,1,0,-1,-2,3 if the sum of n terms is required to be 5 then we will get n=2 and 5(because 1 and -1 will cancel out)
so using formula of sum of n terms
(n/2)(2a+(n-1)d) we get a quadratic equation which will have 2 answers
the reason for 2 answers is after some amount of terms negative terms will start coming so the total sum of n terms will go back the way it started,
for example in the A.p 3,2,1,0,-1,-2,3 if the sum of n terms is required to be 5 then we will get n=2 and 5(because 1 and -1 will cancel out)
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