What are the factors of x2 – 4x – 5? check all that apply. x – 5 x – 2 x – 1 x + 1 x + 2 x + 5

1.  is a 2nd degree polynomial, so if it can be factorize, it can be factorized into two 1st degree polynomials:



2. consider the factorized expression. If we factorized back we would get:



3. So 

comparing the coefficients, we see that 
a+b=4 and ab=-5. 

From ab=-5, a is either 5 (b=-1) or a is -5 (b=1). Together with the condition a+b=4, we see that the right choice is a=5 and b=-1

4. so 

5. The factors are x-5 and x+1