If k is an integer and k^2 -4 > 45 , then which of the following inequalities must be true?
2k > 13
8k > 56
k^2 > 62
k^3 > 512
k^2 > 523
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k^2 > 49crimson2283 wrote:If k is an integer and k^2 -4 > 45 , then which of the following inequalities must be true?
2k > 13
8k > 56
k^2 > 62
k^3 > 512
k^2 > 523
So, k < -7 or k > 7
Since K is an integer , so K could be any integer <= -8 Or >=8.
2k > 13 -> Wrong if k =-8
8k > 56 -> wrong if k =-8
k^2 > 62 - Always right
k^3 > 512 - wrong for any -ve value of K
K^2 > 523 - wrong if K=8
C
Thanks
Anshu
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Anshu
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Thanks so much. I get confused when a question uses inequalities.
Can you please explain this?
If - k^2 > 49, I thought k>7 or k>-7. Since k is an integer, I assumed k could be 8 and -6.
But you say, k<-7 (which is correct as per the OA), please explain why.
Can you please explain this?
If - k^2 > 49, I thought k>7 or k>-7. Since k is an integer, I assumed k could be 8 and -6.
But you say, k<-7 (which is correct as per the OA), please explain why.
anshumishra wrote:k^2 > 49crimson2283 wrote:If k is an integer and k^2 -4 > 45 , then which of the following inequalities must be true?
2k > 13
8k > 56
k^2 > 62
k^3 > 512
k^2 > 523
So, k < -7 or k > 7
Since K is an integer , so K could be any integer <= -8 Or >=8.
2k > 13 -> Wrong if k =-8
8k > 56 -> wrong if k =-8
k^2 > 62 - Always right
k^3 > 512 - wrong for any -ve value of K
K^2 > 523 - wrong if K=8
C
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Sure.crimson2283 wrote:Thanks so much. I get confused when a question uses inequalities.
Can you please explain this?
If - k^2 > 49, I thought k>7 or k>-7. Since k is an integer, I assumed k could be 8 and -6.
But you say, k<-7 (which is correct as per the OA), please explain why.
First Check -6^2 = 36, -5^2 = 25 (less than 49), but -7^2 = 49 , -8^2 = 64 (greater than 49)
Here is the graph for (x^2 > 49) showing the same thing. The area in blue is what we are interested here.
https://www3.wolframalpha.com/Calculate/ ... =360&h=242
Whenever you see something like x^2 > 49 => x^2 > 7^2
reduce it to |x| > 7 , which is the same as x > 7 and x < -7.
Thanks
Anshu
(Every mistake is a lesson learned )
Anshu
(Every mistake is a lesson learned )
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Very well explained. Thanks once again.
anshumishra wrote:Sure.crimson2283 wrote:Thanks so much. I get confused when a question uses inequalities.
Can you please explain this?
If - k^2 > 49, I thought k>7 or k>-7. Since k is an integer, I assumed k could be 8 and -6.
But you say, k<-7 (which is correct as per the OA), please explain why.
First Check -6^2 = 36, -5^2 = 25 (less than 49), but -7^2 = 49 , -8^2 = 64 (greater than 49)
Here is the graph for (x^2 > 49) showing the same thing. The area in blue is what we are interested here.
https://www3.wolframalpha.com/Calculate/ ... =360&h=242
Whenever you see something like x^2 > 49 => x^2 > 7^2
reduce it to |x| > 7 , which is the same as x > 7 and x < -7.
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Try to disprove the answer choices by plugging in different values for k.crimson2283 wrote:If k is an integer and k^2 -4 > 45 , then which of the following inequalities must be true?
2k > 13
8k > 56
k^2 > 62
k^3 > 512
k^2 > 523
Plug in k = -8. This value works because (-8)^2 - 4 > 45.
Answer choice A:
2*(-8) > 13. No.
Elliminate A.
Answer choice B:
8(-8) > 56. No.
Eliminate B.
Answer choice C:
(-8)² > 64. Yes.
Hold onto C.
Answer choice D:
(-8)³ > 512. No.
Eliminate D.
Answer choice E:
(-8)² > 523. No.
Eliminate E.
The correct answer is C.[/spoiler]
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Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.
As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.
For more information, please email me (Mitch Hunt) at [email protected].
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