What a Mathematical Family !!!

My dad teaches me extra portions in Math and on Friday night he was teaching me Quadratic Equations. ( Way ahead of what Im learning in school,(ie) we're in the mid of the 3rd Chapter at school and at home I've finished around 6 chapters).My dad finished the basics I was to do some problem sums.Meanwhile,my mom called my dad to discuss about how much money we had to return to our aunt ( all part of Singapore trip negotiations ).My mom was trying to explain something and my dad coudn't quite understand it and so he took a notebook and it started with substituting a 'x' and a 'y' and then a whole lot of calculations which I didn't wanna understand anyway and then finally emerged triumphant answer. All this because of a simple question - the one above. And meanwhile,I was doing my last sum and was getting a lot exhausted (it's 10:30 pm ).
What I was stuck with was ...

Now , let 'm' be one term ( like ax+b ) and 'n' be another term . I had to find the zero of the polynomial. The last step till where I was correct was "(m)(n) = 0".. Here,according to me ( the before 'me' ), either 'x' had to be '0' or 'y' had to be '0'. Therefore, I got 2 answers for the values of 'x' ( WHich for THIS SUM is wrong ). But the Text Book gave one solution ( which was equal to one of my 2 solutions (ie) m=0) and gave 'n' =/ 0 which confused me ( Hey!...Im a beginer..).

[ whew!! ]

Also, my dad said that I would get my new watch only if my bro gets an A in Further Mathematics
[Yeah....even I dont get the point ]


NOTE : Sincere apologies to those who cannot understand and to those who cannot understand and I hope my seniors can understand if u can't ....I'm in NO position to explain this in a different way.