NECO 2023 · Paper 1 · Q25

Find the values of $x$ for which $g(x) = \dfrac{x^2 - 5x + 6}{x^2 - 5x - 24}$ is undefined.

Worked solution (try it first)

A fraction is undefined where its bottom is zero: $x^2 - 5x - 24 = 0$ .
Two numbers that multiply to $-24$ and add to $-5$ are $-8$ and 3, so $(x - 8)(x + 3) = 0$ .
So $x = 8$ or $x = -3$ , option B.