Question

x²=225-(x+3)² find the equation

Answer 1

Given x^2 = 225 - (x+3)^2

          x^2 = 225 - (x^2 + 6x + 9)

         x^2 = 225 - x^2 - 6x - 9

        x^2 = -x^2  - 6x + 216
 
         2x^2  + 6x - 216 = 0

 We know that x = -b+root b^2 - 4ac/2a

                            = -6 + root 6^2 - 4 * 2 * (-216)/4

                           = - 6 +42/4

                           = 9.    -- (1).



We know that x = -b - root b^2 - 4ac/2a

                          = -6 - 42/4

                          = -12.   --- (2).


From (1)  and (2) , we get x = 9 (or) x = -12.


Hope this helps! :)