Question

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

Answer 1

When you factor (x^2-4x-5), you get (x+1)(x-5).

Answer 2

Answer:

$(x-5)(x+1)$

Step-by-step explanation:

we have

$x^{2} -4x-5$

To find the factors ------> solve the quadratic equation

equate the function to zero

$x^{2} -4x-5=0$

The formula to solve a quadratic equation of the form $ax^{2} +bx+c=0$ is equal to

$x=\frac{-b(+/-)\sqrt{b^{2}-4ac}} {2a}$

in this problem we have

$x^{2} -4x-5=0$

so

$a=1\\b=-4\\c=-5$

substitute

$x=\frac{-(-4)(+/-)\sqrt{-4^{2}-4(1)(-5)}} {2(1)}$

$x=\frac{4(+/-)\sqrt{36}} {2}$

$x=\frac{4(+/-)6} {2}$

$x=\frac{4(+)6} {2}=5$

$x=\frac{4(-)6} {2}=-1$

therefore

the factors are

$(x-5)(x+1)$