Answers

2016-03-12T12:22:02+05:30
A=18
l=-97/2
d=-5/2
n=?
l=a+d(n-1)
-97/2=18+-5/2(n-1)
-97/2-18=-5/2(n-1)
-115/2*-2/5=n-1
23+1=n
n=24
therefore, sn=n/2(a+l)
            =24/2(18-97/2)
            =12*61/2
            =366
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