Question: 2x vs. y+2

Comment on 2x vs. y+2

I divided both sides by 2 and compared as follows.

Quantity A: 2x/2 Quantity B: (y+2)/2
Quantity A: x Quantity B: y/2 + 1

x < y/2 +1
greenlight-admin's picture

That works also! Nice work.

Given that - X<Y/2, we can say => 2x<y
=> 2x A y+2 B
When 2x is greater than y, y+2 is greater than y,
Then y+2 is greater than 2x.

SO B is greater.

How about this conclusion Brent?
greenlight-admin's picture

That approach is perfectly valid, Vineet.

in the case of -y 2xgreater than y , here is not mentioned how much greater, that means might be equal or greater than answer d. it's right?
greenlight-admin's picture

I'm not quite sure I follow your question.
If we take x < y/2 and multiply both sides by 2, we get: 2x < y
Since we also know that y < y + 2, we can combine the two inequalities to get: 2x < y < y + 2, which means the correct answer is B.
Does that help?

After watching you manipulate inequalities in ways that seem VERY simple once you do so, I clearly need to try to use number properties, etc., more often! Sheesh.

That having been said:

1. Manipulate the *given* info one step further than was done in the video:

Given info:

x < y/2
(multiply both sides by 2):
2x < y
(subtract y from both):
2x-y < 0
That is, (2x-y) is negative.

2. Now manipulate the Quantities. Given:

Qty A: 2x
Qty B: y+2

3. Subtract y from both to get:

Qty A: 2x-y
Qty B: 2

4. We know that 2x-y is negative. (Above, 2x-y<0), so we have:

Qty A: something NEGATIVE
Qty B: 2 (= POSITIVE)

Qty B is greater.
greenlight-admin's picture

That's a perfect solution - great work!

given x < y/2 (x2 both sides) to get 2x < y since 2 is +ve and doesn't change the inequality sign. we can now see that 2x < y so obviously 2x < y + 2. cheers
greenlight-admin's picture

Very nice!

Have a question about this video?

Post your question in the Comment section below, and a GRE expert will answer it as fast as humanly possible.

Change Playback Speed

You have the option of watching the videos at various speeds (25% faster, 50% faster, etc). To change the playback speed, click the settings icon on the right side of the video status bar.

Let me Know

Have a suggestion to make the course even better? Email us today!

Free “Question of the Day” emails!