You don't, if you're only looking for real number results. If you are including imaginary numbers, x2+4 = (x+2i)*(x-2i).
(2x - 1)(2x + 3)
(a + x^2)(b + y^2)
No
x2y + axy + abx + a2b Factor by grouping. xy(x + a) + ab(x + a) (xy + ab)(x + a)
(x+1)(x+8)
(x + 2)(x + 1)
(x + 3)(x + 3)
(x + 3)(x + 2)
4(x+y)^2
it is (x-y)(x-y) :)
(x-5i)(x+5i)
(x + 5)(x + 1)