Question

sum of first n term of the series _/2+_/8+_/18 +... is __(a)n(n+1)/2 (b)_/n (c)n(n+1)/_/2 (d) 1​

Answer 1

Answer:

option c is correct

Step-by-step explanation:

Sn=n/2×(2a+(n-1)d)

n = ? d= 2root2 - root2 a= root2

Sn=n/2×(2root2+(n-1)(2root2-roo2)

Sn=n/root2×root2 × (2root2+2root2n - 2root2 - root2n+ root2)

Sn=n/root2×root2 × root2×(2n-n+1)

Sn=n(n+1)/root2

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