the sum of first 7 terms of an ap is 49 and sum of the first 17 terms is 289 find the sum of first n terms????
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Satan2002:
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s7=49
s17=289
s7=n\2(2a+(n-1)d)
aS we know s7=49...so
47=7\2(2a+(7-1)d
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7a+21d=47 ....by just following this find the second equation and elemenate both the equations to get the value of a and d by which you would be able to find the value of n terms
s17=289
s7=n\2(2a+(n-1)d)
aS we know s7=49...so
47=7\2(2a+(7-1)d
...
...
...
7a+21d=47 ....by just following this find the second equation and elemenate both the equations to get the value of a and d by which you would be able to find the value of n terms
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