Question

Use factor theorem to determine whether x + 3 is factor of x ² + 2x − 3 or not.

Answer 1

Let p(x) = x² + 2x − 3.

Divisor = x + 3

$\therefore p\left(-3\right)={\left(-3\right)}^2+2\times \left(-3\right)-3=9-6-3=0$

So, by factor theorem, (x + 3) is a factor of x² + 2x − 3.