NECO 2024 · Paper 1 · Q24

If $(x + 6)$ is a factor of $x^2 + 4x - 12$ , find the other factor.

Worked solution (try it first)

The other factor is $(x + b)$ , where $6 \times b = -12$ (the constant term).
So $b = -2$ .
Check the middle term: $6 + (-2) = 4$ , which matches $4x$ .
So $x^2 + 4x - 12 = (x + 6)(x - 2)$ and the other factor is $(x - 2)$ , option A.