Question

In the following, find the value of k for which the given value is a solution of the given equation:

x² + 3ax + k = 0, x = -a

Answer 1

We are given here that,

x² + 3ax + k = 0, x = -a

Now, as we know that x = -a is a solution of the quadratic equation, hence it should satisfy the equation. Therefore substituting x = -a in the above equation gives us,

x² + 3ax + k = 0

(-a)² + 3a(-a) + k =0

a² - 3a² + k = 0

-2a² + k = 0

k = 2a²

Hence the value of k = 2a².