Multiple choice

If roots of the quadratic equation $3y^2+ky+12=0$ are real and equal, then find k.

  1. $12$
  2. $-12$
  3. $\pm 12$
  4. $\pm 13$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

For real and equal roots, the discriminant b^2 - 4ac = 0. k^2 - 4(3)(12) = 0. k^2 - 144 = 0. k^2 = 144, so k = +/- 12.

AI explanation

For a quadratic equation to have real and equal roots, its discriminant must equal zero. Using the discriminant formula b^2 - 4ac, we substitute the given values to get k^2 - 4(3)(12) = 0. Solving k^2 - 144 = 0, we find k^2 = 144, which means k = 12 or k = -12. Therefore, the value of k is plus or minus 12. The correct result is plus or minus 12.

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