Angalia hii!
Let a=b, upo sawa
then ab=b^2, it's ok
ab-a^2=b^2-a^2, true.
Olso a(b-a)=(b-a)(b+a) it's ok!
But, u can't divide throughout by (b-a) since a=b, then b-a=0. So the equation is meaningless since you are trying to dived by zero. Kwahiyo basi, moja haiwezi kuwa sawa na mbili hata...