Number Properties page 86 number 5

[laura.a.hague]

|x|>|y|. Which of the following must be true? Indicate all that apply.
A. xy is positive
B. x+y>0
C. x squared > y squared

The answer in the book is C.

My answer was A, B, C because |x| indicates absolute value, does it not? Meaning both numbers, where negative or positive within | | will be positive values, therefore making all three choices correct. Am I wrong?

[tommywallach]

Hey Laura,

You're mistaking the point, x and y don't have to be positive, just absolute value of x and y. So, for statement A, we could have:

x = -3 and y = 2

The absolute values would make the inequality true, because absolute value of -3 is bigger than the absolute value of 2. But in this case, xy would be negative.

See?

-t