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Comment on Factoring - Difference of Squares
https://gre.myprepclub.com/forum
I understand how you got the answer here but isn't option D also possible?
Can you tell me how you
Can you tell me how you determined D is also correct?
Otherwise, so it's hard for me to tell what show why it isn't correct.
If it helps, I also posted the question here (https://gmatclub.com/forum/if-j-2-4-6-8-98-100-and-k-239753.html) via may GMAT prep company.
It may help to see other students' solutions.
Cheers,
Brent
I took the first 5 values of
J: 2,4,6,8,10
K:1,3,5,7,9
K^2 - J^2 =
1^2 - 2^2 = 1-4 = -3
3^2 - 4^2 = 9-16 = -7
5^2 - 6^2 = 25 - 36 = -11
7^2 - 8^2 = 49-64 = -15
9^2 - 10^2 = 81-100 = -19
Have i gotten this terribly wrong?
Your idea to test a smaller
Your idea to test a smaller case is great!
Let's take this strategy all the way to the end.
In this case,
J = 2 + 4 + 6 + 8 + 10 = 30
K = 1 + 3 + 5 + 7 + 9 = 25
From your calculations, we get:
1² - 2² + 3² - 4² + 5² - 6² + 7² - 8² + 9² - 10² = (-3) + (-7) + (-11) + (-15) + (-19)
= -55
So, given the values of J (30) and K (25), which answer choice evaluates to be -55?
C) -K - J = -25 - 30 = -55 PERFECT!
D) K² - J² = 25² - 30² = 625 - 900 = -275
Since answer choice D does not evaluate to be -55, it cannot be the correct answer.
How's that?
Cheers,
Brent
Hi Brent, can you explain
I'm wondering how you determined x squared > y squared in the inequality... Did you just square both sides since x and y are positive?
Question link: https:/
Question link: https://gre.myprepclub.com/forum/1-x-y-8383.html
In the question we're told that 0 < y < x
In other words, x and y are both positive numbers, and y is smaller than x
We then take y (the smaller number) and multiply it by y (the smaller number) to get y²
We also take x (the bigger number) and multiply it by x (the bigger number) to get x²
As you might guess, the result is that y² is less than x²
Does that help?