Find the sum+ +
Use the identity= , which gives you = . <<<---=== it is how to "rationalize the fraction" in this case (!) In this way, = = <<<---=== in this case a= 2; b= 1. = = ; <<<---=== in this case a= 3; b= 2. = = <<<---=== in this case a= 4; b= 3. So, the long sum of three fractions is equal to + + = . ANSWER