Question

The product of two numbers is 120 and the sum of their squares is 289. The sum of the number is:

Answer 1

consider the two number be x and y
               xy=120
               x^2+y^2=289
       then x+y=is the question
         formula (x+y)^2=x^2+y^2+2xy
                                =289+2(120)
                                 =289+240
                                 =529
                     (x+y)^2=529, taking square root on both side
                 then x+y=23
the sum of the number is 23