.
According to the Vieta's theorem, the product of the roots is equal to the value of the constant term of a polynomial.
Since the number 3 is the root and since the constant term is 15, then the second root is
= 5.
According to the Vieta's theorem, the sum of the roots is equal to the coefficient at x taken with the opposite sign.
Since the roots are 3 and 5, it implies that k = -(3+5) = -8. ANSWER
Solved. The value of "k" is -8: Option B).