[tex](4x+5y)(2x-3y)+3xy=(4x)(2x)+(4x)(-3y)+(5y)(2x)+(5y)(-3y)+3xy\\\\=8x^2-12xy+10xy-15y^2+3xy\\\\\text{combine like terms}\\\\=8x^2-15y^2+(-12xy+10xy+3xy)=8x^2-15y^2+xy[/tex]
[tex]6x^2+11x+4=6x^2+3x+8x+4=3x(2x+1)+4(2x+1)\\\\=(2x+1)(3x+4)[/tex]
[tex]10x^2+19x+6=10x^2+15x+4x+6=5x(2x+3)+2(2x+3)\\\\=(2x+3)(5x+2)[/tex]
