(x + y)(x - 3y)
9 - x2 will factor into (3 - x)(3 + x)
x2(x3 + 1) is the best you can do there.
x2-9x = x(x-9)
If you mean "factors", the two monomials have the common factor x2. Divide each factor by x2 to get the other factor.
x2-49 = (x-7)(x+7)
x2 - 4
9 - x2 will factor into (3 - x)(3 + x)
x2-3x-28
x2-14 does factor but not pretty; it factors to: (x+sqrt14)(x-sqrt14).
x2 + 6x - 2 can not be factored
x2(x3 + 1) is the best you can do there.
x2-9x = x(x-9)
x2-x=x(x-1)
x2 - 13 + 30 = x2 + 17, which has no real factors.
x2-6x can be factored into x(x-6). Simply factor out the "x" from both factors.
If you mean "factors", the two monomials have the common factor x2. Divide each factor by x2 to get the other factor.
That does not factor neatly.