If the quadratic equation x² + 4x + k = 0 has roots that are real numbers, what is the minimum value of k?
Answer: C. -4
For the roots to be real, the discriminant must be non-negative: b² - 4ac ? 0. Here, 4² - 4(1)(k) ? 0 leads to 16 - 4k ? 0, thus k ? 4. The minimum value of k is -4.