1.

The sum of `n` terms of the series `1/(sqrt1+sqrt3)+1/(sqrt3+sqrt5)+...` isA. `sqrt(2n+1)`B. `(1)/(2)sqrt(2n+1)`C. `sqrt(2n+1)-1`D. `(1)/(2)(sqrt(2n+1)-1)`

Answer» Correct Answer - D
The required sum to n terms is given by
`(1)/(sqrt(1)+sqrt(3))+(1)/(sqrt(3)+sqrt(5))+(1)/(sqrt(5)+sqrt(7))+ . . .+(1)/(sqrt(2n-1)+sqrt(2n+1))`
`=(1)/(2)[(sqrt(3)-sqrt(1))+(sqrt(5)-sqrt(3))+(sqrt(7)-sqrt(5))+(sqrt(2n+1)-sqrt(2n-1))]`
`=(1)/(2)(sqrt(2n+1)-1)`


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