How many terms of the AP -6,-11/5,-5,.......are needed to give the sum -25 ? Explain the double answer.
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a=-6
d=a2-a1
=11÷5-(-6)
=8.2
sn=-25
sn=n÷2(2a(n-1)d)
-25 =n÷2(2×(-6)(n-1)8.2)
-25×2=n
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