Each of the following equations has at least one solution EXCEPT?
-2^n = (-2)^-n
2^-n = (-2)^n
2^n = (-2)^-n
(-2)^n = -2^n
(-2)^-n = -2^-n
MGCAT....700 - 800Q
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plug in -1,1,0 (-ve, +ve odd and even) into answer choices and check
a) -2^n = (-2)^-n has no solution -> -2^-1=(-2)^+1, -2^1=(-2)^-1 and -2^0=(-2)^0 {pemdas https://www.beatthegmat.com/mba/2011/02/ ... arithmetic , -1*2^0=(-2)^0 <> -1=1}
IOM a
a) -2^n = (-2)^-n has no solution -> -2^-1=(-2)^+1, -2^1=(-2)^-1 and -2^0=(-2)^0 {pemdas https://www.beatthegmat.com/mba/2011/02/ ... arithmetic , -1*2^0=(-2)^0 <> -1=1}
IOM a
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- neerajkumar1_1
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hi,
follow the link...
https://www.beatthegmat.com/at-least-one ... 66137.html
Also logically
option A is the only one which has no solution
imagine can - 2^n = (-1/2)^n ???
it will never be equal to each other...
best case... try putting n=0
u will get -1 = 1
otherwise though with odd powers of n u can match the sign on either side of the equation... but u will never be able to match the value 2 to 1/2
hope it helps...
follow the link...
https://www.beatthegmat.com/at-least-one ... 66137.html
Also logically
option A is the only one which has no solution
imagine can - 2^n = (-1/2)^n ???
it will never be equal to each other...
best case... try putting n=0
u will get -1 = 1
otherwise though with odd powers of n u can match the sign on either side of the equation... but u will never be able to match the value 2 to 1/2
hope it helps...
- GMATGuruNY
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Find the four answer choices that each have a solution.Each of the following equations has at least one solution EXCEPT:
A. -2^n = (-2)^-n
B. 2^-n = (-2)^n
C. 2^n = (-2)^-n
D. (-2)^n = -2^n
E. (-2)^-n = -2^-n
Values likely to work in a majority of the answer choices are n=0 and n=1.
Plug n=0 and n=1 into the answer choices:
A. -2^n = (-2)^-n
n=0:
-(2^0) = (-2)^-0
-1 = 1. Doesn't work.
n=1:
-(2^1) = (-2)^-1
-2 = -1/2. Doesn't work.
Hold onto A.
B. 2^-n = (-2)^n
n=0:
2^-0 = (-2)^0
1=1.
n=0 is a solution. Eliminate B.
C. 2^n = (-2)^-n
n=0:
2^0 = (-2)^-0
1=1.
n=0 is a solution. Eliminate C.
D. (-2)^n = -2^n
n=1:
(-2)^1 = -(2^1)
-2 = -2.
n=1 is a solution. Eliminate D.
E. (-2)^-n = -2^-n
n=1:
(-2)^(-1) = -(2^-1)
-1/2 = - 1/2
n=1 is a solution. Eliminate E.
The correct answer is A.
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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].
Student Review #1
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