Which term of AP 5,2,-1,.........is -49

1.	Which term of AP 5,2,-1,.........is -49
Answer» a=5d= -3 Using formula an =a+(n-1)d-49= 5+(n-1)-3-49-5=-3(n-1)-54=-3(n-1)-54/3=(n-1)18=(n-1)n=19

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