Hey this is worked out sum from my book and I am having a bit problem in understanding it 1. The problem statement, all variables and given/known data (It's a pure quadratic equation) If (35-2x)/9+(5x 2+7)/(5x 2-7)=(17-2/3x)/3 find x Well its worked out well till (5x 2+7)/(5x 2-7)=16/9 and the comes the real confusion is Its given 5x 2/7= (16+9)/(16-9)=25/7 [componendo and dividendo] What is this" componendo and dividendo"?:uhh: I don't know !Please help! Another e.g. is √( 3x^2-7x-30)-√(2x^2-7x-5)=x-5 then they write Identically (3x^2-7x-30)-2x^2-7x-5)=x^2-25(!!!???) Is this also by the same" componendo and dividendo"? Plz help me out!! I really don't this componendo and dividendo !!