Tortugamx wrote:
This question can be answered in a few seconds. Given that it is a quadratic expression, z must have exactly two solutions. Even if one solution were sqrt(20), in which case A would equal B, the other solution would be a different number, whose sqrt would not be 20. Therefore the answer is D.
That isn't entirely correct, and it could get you in trouble with other questions.
First of all, quadratic equations can have 0, 1 or 2 different solutions.
x² + 2x + 32 = 0 has zero solutions.
x² - 2x + 1 = 0 has 1 solution (x = 1).
x² - 2x - 15 = 0 has 2 solutions (x = 5 and x = -3).
Even if the equation has two solutions, this doesn't mean that the correct answer is automatically D.
Consider, for example, this question:
x² + 2x - 15 = 0
QUANTITY A: x²
QUANTITY B: 4
In this case, even though the given equation has two possible solutions, the correct answer is A.