If `sum_(k=4)^(143) (1)/(sqrt(k)+sqrt(k+1))=a-sqrt(b)` then a and b re – InterviewSolution

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1.	If `sum_(k=4)^(143) (1)/(sqrt(k)+sqrt(k+1))=a-sqrt(b)` then a and b respectively areA. 10 and 0B. `-10 and 4`C. 10 and 4D. `-10 and 0`
Answer» Correct Answer - A (i) Substitute the values of k and rationalize every term of LHS. (ii) `underset(k=4)overset(143)sum(1)/(sqrt(k)+sqrt(k+1))=(1)/(sqrt(5)+sqrt(4))+(1)/(sqrt(6)+sqrt(5))+...+(1)/(sqrt(144)+sqrt(143))` (iii) Rationalize the denominator two times.

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