Question

What are the factors of $x^2+5x-24$?

• A. $(x-3)(x-8)$
• B. $(x-3)(x+8)$
• C. $(x+3)(x+8)$
• D. $(x+3)(x-8)$

Answer 1

The correct option is B $(x-3)(x+8)$

$x^2+5x-24$
Split the middle term, $5x$. Since 24 is a multiple of 3 and the difference between 3 and 8 is 5, splitting into $-3x$ and $8x$ would be a good choice.
$x^2-3x+8x-24$
$x(x-3)+8(x-3)$
Taking $(x-3)$ to be common
$(x-3)(x+8)$