Multiple choice

If one of the roots of the equation $kx^2 - 7x + 3 = 0$ is $3,$ then $k =$ ..............

  1. $-3$
  2. $3$
  3. $-2$
  4. $2$
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D Correct answer
Explanation

If 3 is a root, k(3)^2 - 7(3) + 3 = 0. 9k - 21 + 3 = 0. 9k = 18. k = 2.

AI explanation

Substitute the root x = 3 into the quadratic equation kx^2 - 7x + 3 = 0. This gives the equation k(3)^2 - 7(3) + 3 = 0, which simplifies to 9k - 21 + 3 = 0 or 9k - 18 = 0. Solving for k gives 9k = 18, so k = 2.

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