Odpowiedzi

2010-01-29T01:22:13+01:00
4 - x² + 2xy - y² =

4 - 2(xy - (x²/2) - (y²/2)) =

2(2 - (xy - (x²/2) - (y²/2)) =

2( 2 - (xy - (x²-y²)/2)
2 1 2