What is the factored form of x2 - 4x - 5?

A. (x + 5) (x - 1)

B. (x + 5) (x + 1)

C. (x - 5) (x - 1)

D.; (x - 5) (x + 1)

The answer would be D ...

When the coefficient in front of the x^2 term is 1 you can factor a quadratic by finding two numbers such that the sum is the coefficient infront of x and the product is c. So

a+b=-4 and ab=-5 notice that - 5 and 1 are solutions since (-5) * 1=-5 and 1-5=-4 so you can factor it as (x-5) (x+1).