how to proving a square root equality? Look the right side of the equation, all numbers are inside the square root, so in left side of the equation first step is to move the number into inside
of the square root. Look the right side of the equation, there are two terms inside of the square root. so in the left side of the equation we need to subtract 6 and add 6.
since the numerator has a common factor 6, so we need to put the common factor 6 outside the parenthesis. Inside the parenthesis the factor 6^{2} - 1 is
exactly the denominator. Remove the common factor 6^{2} - 1 and we get the answer.