1)а²-а-6; 2)6а²+5а-4; 3)20х²-13ху+2у².

[latex]a^2-a-6\\a_{1,2}=\frac{1^+_-5}{2}\\a_1=3\ ;a_2=-2\\a^2-a-6=(a-3)(a+2)\\\\6a^2+5a-4\\a_{1,2}=\frac{-5^+_-11}{12}\\a_1=\frac{1}{2}\ ;a_2=-\frac{4}{3}\\6a^2+5a-4=3*2(a-\frac{1}{2})(a+\frac{4}{3})=(2a-1)(3a+4)\\\\20x^2-13xy+2y^2=20x^2-5xy-8xy+2y^2=5x(4x-y)-2y(4x-\\-y)=(5x-2y)(4x-y)[/latex]