.
HINT. Multiply each denominator (and numerator) by the conjugate number to the denominator.
In each denominator, you will get the value of 1.
The numerators will form alternated sequence.
As a result, all intermediate terms will cancel each other, and you will get the combination
of the last and the first terms as your answer.
ANSWER. 5*sqrt(36) - 5 = 5*6 - 5 = 25.
See the lesson
- Amazing calculations with fractions that contain quadratic irrationalities in denominators
in this site, Problem 4.
Your problem is solved there with all detailed explanations.