Factorise the quadratic polynomial by splitting the middle term:
x2 + 14x + 45
(x + 9) (x + 5)
x2 + 14x + 45
here a = 1, b = 14, c = 45
ac = 45 = 9 X 5 , b = 14 = 9 + 5
x2 + 14x + 45
= x2 + 9x + 5x + 45
= x( x + 9 ) + 5(x + 9)
= (x + 9) (x + 5