x² + 5x – 104

Now, first we have to find out the numbers whose-

Sum = 5 and

Product = - 104

The numbers are 13 and 8,

So,

x² + 5x – 104 = x² + 13x – 8x – 104

= x(x + 13) – 8(x + 13)

= (x + 13)(x – 8)