Question

One of the solutions to x2 − 2x − 15 = 0 is x = −3. what is the other solution?

Answer 1

x² - 2x - 15 = 0 comparing to ax² + bx + c = 0, a = 1, b = -2, c = -15.

sum of roots = -b/a = -(-2)/1 = 2

-3 + other solution = 2

other solution = 2 + 3

other solution = 5

Answer 2

x = 5

Explanation:

To find the other solution of a quadratic equation, one of the options available to solving it is by factorization.

Given;

x2 − 2x − 15 = 0

x2 - 5x + 3x - 15 = 0

x(x - 5) +3(x - 5) = 0

(x + 3)(x - 5) = 0

x = -3 or x = 5

Given that x = −3 is one of the options, the other is x = 5