One minor correction on your question here - it's not a binomial. A binomial is a polynomial with two terms. This one - having three terms, is a trinomial.
To factor it, you need to find two numbers that multiply to make -45 (the last term), and add to make 4 (the coefficient of the middle term). Once you have those numbers, you can break the equation down. In this case the numbers we need are 9 and -5. Here's how it's done:
x2 + 4x - 45
= x2 - 5x + 9x - 45
= x(x - 5) + 9(x - 5)
= (x + 9)(x - 5)
x + 4
(x - 14)(x - 2)
(x - 5)(x - 8)
A binomial
X2 + 2X - 35 What two factors of - 35 add up to 2? (X - 5)(X + 7) -----------------
x + 4
x2-12x+35 = (x-5)(x-7)
The factors are (x + 6) and (x - 3)
(x - 14)(x - 2)
(x - 5)(x - 8)
A binomial
(x + 10) and (x + 4) are both factors
X2 + 2X - 35(X - 5)(X + 7)================take your pick of these two binomials
x2-7x-44 (x-11)(x+4)
X2 + 2X - 35 What two factors of - 35 add up to 2? (X - 5)(X + 7) -----------------
x2-64 = (x-8)(x+8) when factored
(x + 1)(x + 5)