Multiple choice

If one root of the quadratic equation $x^{2}\,-\,7x\,+\,k\,=\,0$ is 4, then find the value of $k$.

  1. 10

  2. 11

  3. 12

  4. 13
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

If 4 is a root, then 4^2 - 7(4) + k = 0. 16 - 28 + k = 0, so -12 + k = 0, which means k = 12.

AI explanation

Substitute the given root x equals 4 directly into the quadratic equation x squared minus 7x plus k equals 0. This results in 4 squared minus 7 times 4 plus k equals 0. Calculating the values gives 16 minus 28 plus k equals 0. Simplifying this yields minus 12 plus k equals 0, which means k equals 12.

Keep practicing — related questions