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Comment on Fractions with x and y
A quick way I arrived at the
First realised that x and y are negative,but that x is greater in magnitude than y (i.e. x is more negative than y). When you divide 1 by a negative number you get a negative fraction; the more negative the denominator the smaller in magnitude the result is (and therefore the less negative it is).
So we are taking a less negative number away from a more negative number, which leaves us with something still on the negative side of the number line.
This explanation is lengthy, but if you realise that about the question, it's a quick way to solve it I think.
I love it! That's a great
I love it! That's a great (and perfectly valid) solution that uses some number sense.
May i know why is it that i
Given:
Given:
QUANTITY A: 1/2y - 1/2x
QUANTITY B: 0
Be careful, if we multiply Quantity A by 2, we don't get y - x.
If we multiply both quantities by 2, we get:
QUANTITY A: 2/2y - 2/2x
QUANTITY B: 0
Simplify to get:
QUANTITY A: 1/y - 1/x
QUANTITY B: 0
That said, let's keep going.
The given information tells us that x and y are both negative.
This means the product xy is POSITIVE
So, let's multiply both quantities by xy to get:
QUANTITY A: xy/y - xy/x
QUANTITY B: 0
Simplify to get:
QUANTITY A: x - y
QUANTITY B: 0
At this point, we can add y to both quantities to get:
QUANTITY A: x
QUANTITY B: y
Since we're told that x < y < -1, we can see that Quantity B is greater.
Does that help?
Cheers,
Brent
Hi Brent, at this stage if I
Simplify to get:
QUANTITY A: x - y
QUANTITY B: 0
At this point, minus x to both quantities to get:
QUANTITY A: -y
QUANTITY B: -x
Multiply with negative sign to both sides
QUANTITY A: y
QUANTITY B: x
So A > B. Not sure what have gone wrong here? Could you help? Thanks
If you use the matching
If you use the matching operations strategy, you CAN'T multiply (or divide) both quantities by a negative value.
You might want to re-watch this video: https://www.greenlighttestprep.com/module/gre-quantitative-comparison/vi...
noted thanks
if we solve x-y/2xy; here 2xy
Almost!
Almost!
Since x < y, we know that x-y is NEGATIVE (not positive)
So, Quantity A is negative
Pick x = -3, y = -2 and solve
Be careful. Getting B as the
Be careful. Getting B as the correct answer was only coincidental.
Testing ONE set of possible values will not yield a definitive answer here.
When you plug in x = -3 and y = -2 and see that Quantity B > Quantity A, this just tells you that the correct answer is either B or D. That's all you can be certain of. It just happens to be the case that Quantity B is always greater.
I cover this at 2:50 in the following video: https://www.greenlighttestprep.com/module/gre-quantitative-comparison/vi...