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Comment on k's on Both Sides
This is definitely a quicker
Your method is great (however
Your method is great (however, when you replaced k with 1, you should have found that the two quantities are equal). In fact, the strategy you used is covered in this video: https://www.greenlighttestprep.com/module/gre-quantitative-comparison/vi...
The strategy I used is called Matching Operations. It's covered here: https://www.greenlighttestprep.com/module/gre-quantitative-comparison/vi...
my way was to plug some
That works too! Just keep in
That works too! Just keep in mind that plugging in numbers only yields a conclusive result when the answer is D. For more see https://www.greenlighttestprep.com/module/gre-quantitative-comparison/vi... (starting at 2:50)
So in a question like this
Those are the steps I took
Those are the steps I took for this question, but I would advise against memorizing steps. Just follow the basic guidelines/rules that we cover in this related video: https://www.greenlighttestprep.com/module/gre-quantitative-comparison/vi...
Notice that I could have taken a different route (while still adhering to the rules of Matching Operations (as covered in the above video). For example...
QUANTITY A: 3k + 5
QUANTITY B: 11 - 3k
Subtract 5 from both quantities to get:
QUANTITY A: 3k
QUANTITY B: 6 - 3k
Add 3k to both quantities to get:
QUANTITY A: 6k
QUANTITY B: 6
Divide both quantities by 6 to get:
QUANTITY A: k
QUANTITY B: 1
Answer: D
Hello! I dont understand the
Hi Dsho,
Hi Dsho,
Here, the two quantities are expressions.
So, Quantity A and Quantity B can have a variety of values, depending on the value of k.
Regarding the technique used to answer the question, this video covers everything you need to know: https://www.greenlighttestprep.com/module/gre-quantitative-comparison/vi...
Please let me know if that helps.
Cheers,
Brent
Hi!
I have a question.
I approach this question by squaring both sides, so I could exclude K and get only positive integers. Why was my solution wrong?
That strategy can get you
That strategy can get you into trouble, because squaring a NEGATIVE will turn that number into a POSITIVE number.
Consider this example:
QUANTITY A: 2
QUANTITY B: -3
We can clearly see that Quantity A is bigger
However, if we SQUARE both quantities, we get:
QUANTITY A: 4
QUANTITY B: 9
Now Quantity B is bigger
Also, keep in mind that we're already told that k is positive (k > 0)
Cheers,
Brent
First check for equal case -
Assume they are equal => 3k+5 = 11-3k
Simplify, get k=1 so when K is 1 both quantities are equal.
At this point we know that we met the equal case,
Now, check for inequality case => plug k=2 in both the quantities.
3(2)+5 11-3(2)
11 11-6 ----> here clearly A is greater.
As such we have 2 answers. The right answer is D
Perfectly valid approach -
Perfectly valid approach - nice work!