x² – 11x – 42

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

Sum = - 11 and

Product = - 42

The numbers are 14 and 3,

So,

x² – 11x – 42

= x² – 14x + 3x – 42

= x(x – 14) + 3(x + 14)

= (x – 14)(x + 3)