Advanced MathEasy–MediumSecond factor of a trinomial
Advanced Math practice question
For all values of x, x² − 7x + 12 = (x − 3)(x − k), where k is a constant. What is the value of k?
Answer: 4
The factors of 12 that add to 7 are 3 and 4, so the other factor is (x − 4).
Common wrong answers
- If you answered 7
- 7 copies the middle coefficient.
- If you answered 12
- 12 copies the constant term.
- If you answered -4
- −4 would give (x − 3)(x + 4) = x² + x − 12.
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