To find the other solution of the quadratic equation x² + 2x – 15 = 0, we can start by using the fact that one solution is x = 3. We can perform synthetic division or simply use the quadratic formula. However, a quicker method is to factor the equation.
The equation can be rewritten as:
x² + 2x – 15 = (x – 3)(x + 5) = 0
Setting each factor to zero will give us the solutions:
- x – 3 = 0 ⇒ x = 3
- x + 5 = 0 ⇒ x = -5
Since we already know that one of the solutions is x = 3, the other solution to the equation is x = -5.