x² - 9x - 10 is equal to :

1. (x - 10) (x + 1)

2. (x - 10) (x - 1)

3. (x + 10) (x - 1)

4. (x + 10) (x + 1)

x² - 9x - 10

= x² - (10 - 1)x - 10

= x² - 10x + 1x - 10

= (x² - 10x) + (1x - 10)

= x (x - 10) + 1(x - 10)

= (x - 10)(x + 1)

Hence, option 1 is the correct option.