1.

Sn=n÷2(2×37+(n-1)2Find value of "n"

Answer»

Answer:

Answer

S=

2

n(n+1)

⇒231=

2

n(n+1)

⇒n

2

+n−462=0

⇒n

2

+22n−21n−462=0

⇒n(n+22)−21(n+22)=0

⇒(n+22)(n−21)=0

⇒n=−22 or n=21

∴n=21 as n=−22 is not a natural NUMBER.


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