apparently simple question becomes a tricky question

[galtgallery]

8.
Column A Column B

x< 0 < y

-x3y 0


COLUMN A is: -x(cubed)y
COLUMN B is: ZERO (0)

A. The quantity in Column A is greater.
Incorrect answer.

B. The quantity in Column B is greater.

C. The two quantities are equal.

D. The relationship cannot be determined from the information given.

Explanation: The correct answer is a. The value of x is negative. x3 is also negative because three negatives multiply to a negative answer. The negative in front of -x3y negates the negative of x3, making the quantity positive. The value of y doesn't matter because it is positive. Therefore, the value of quantity A is positive and greater than quantity B.


This seems very tricky. I understand the math, but the negative sign here seems to have two functions A) to make the x negative and B) to negate the negative X.

This seems similar to an absolute value question, but I have not seen it in this format. Is this accurate? Can you explain or comment? Thanks!

[esledge]

This question is about order of operations. PEMDAS: Parentheses, Exponents, Multiplication, Division, Addition, Subtraction.

In Quantity A, we have an exponent (on the x) that must be dealt with before the multiplication by both y and -1.

For problems like this, I find that it helps me to put "reminder" parentheses in as I write the expression. Quantity A is -x^3y, but I would write this as (-1)*(x^3)*(y). It makes it easier to see that this is (negative)*(negative)*(positive).

I hope this helps!