Question

what are the factors of $x^2 - 4x - 5$? check all that apply. $\square\\ x - 5$ $\square\\ x - 2$ $\square\\ x - 1$ $\square\\ x + 1$ $\square\\ x + 2$ $\square\\ x + 5$

Explanation:

Step1: Find pair for -5, sum to -4

We need two numbers that multiply to $-5$ and add to $-4$. These numbers are $-5$ and $+1$.

Step2: Factor the quadratic

Write the quadratic as a product of two binomials using the found numbers:
$$x^2 - 4x - 5 = (x - 5)(x + 1)$$

Answer:

$\boldsymbol{x-5}$, $\boldsymbol{x+1}$