**Componendo and dividendo** is a method of simplification in mathematics.

**According to it**,

This proof is invalid for a=b and c=d because if

- such that
*a*=*b*&*d*=*c*

then by application of componendo and dividendo we get {a=b,c=d} and since division by zero is not defined :

Posted by Gunjan(student)on 26/2/11