[tex]x*y=2xy+6(x+y)+15\\x*y = 2xy+6x+6y+15\\x*y =2x(y+3)+6(y+3)-3\\x*y = (2x+6)(y+3)-3\\x*y = 2(x+3)(y+3)-3 \\ \\(-2014)*(-2013)*...* 2013 * 2014= \\ \\ = (-2014)*(-2013)*...*(-4)*(-3)*(-2)*...*2013 * 2014\\ \\ \text{Notam }(-2014)*(-2013)*...*(-4) = a\\ \text{Notam }(-2)*...*2013 * 2014 = b \\ \\ a* (-3)*b = \Big(a*(-3)\Big)*b =\Big(2(a+3)(-3+3)-3\Big)*b = \\\\=(-3)*b = 2(-3+3)(b+3)-3 = -3 < 2[/tex]
