Question

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

Answer 1

1. $x^{2} -4x-5$ is a 2nd degree polynomial, so if it can be factorize, it can be factorized into two 1st degree polynomials:

$x^{2} -4x-5=(x-a)(x-b)$

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

$(x-a)(x-b)=xx-bx-ax+ab= x^{2} -(a+b)x+ab$

3. So $x^{2} -4x-5=x^{2} -(a+b)x+ab$

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 $x^{2} -4x-5=(x-a)(x-b)=(x-5)(x-(-1))=(x-5)(x+1)$

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

Answer 2

Answer:

its x-5 and x+1

Step-by-step explanation:

just did it and got it right