Multiple choice

If the coefficient of $x$ in the quadratic equation $x^{2}+px+q=0$ was taken as $17$ in place of $13$, then its roots were found to be $-2$ and $-15$. The roots of the original equation are

  1. $4, 9$
  2. $-4, -9$
  3. $3, 10$
  4. $-3, -10$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The roots -2 and -15 correspond to the equation x^2 + 17x + 30 = 0 (since sum = -17, product = 30). The original equation had 13 instead of 17, so it is x^2 + 13x + 30 = 0. Factoring gives (x + 10)(x + 3) = 0, so the roots are -3 and -10.

AI explanation

The incorrectly recorded equation was x^2 + 17x + q = 0, and its roots are given as -2 and -15. We find the constant term q by multiplying the roots: (-2) * (-15) = 30. The original equation is x^2 + 13x + 30 = 0. Factoring this gives (x + 3)(x + 10) = 0, so the roots of the original equation are -3 and -10.