If the quadratic equations x2 - kx - 49 = 0 and x2 - 5kx + 11 = 0 (where k > 0) have a common root, then the value of k is:

Which of the following equations has the sum of its roots equal to 3?

The quadratic equation corresponding to the roots 1 + √3 and 1 - √3 is:

The equation x4 - 5x2 + 4 = 0 is reducible to a quadratic equation by substituting: