(x-y)^4?
stmt1,
x*y=7
There are many values possible for x and y.
Insuff
stmt2,
x and y are integers
We don't know values for x and y.
Insuff
Combining 1 and 2,
x*y=7
x and y are integers
x=`1,y=7 or x=7,y=1 value of (x-y)^4=36^2
Suff
Pick C
Integer
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Source: Beat The GMAT — Data Sufficiency |
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neerajkumar1_1
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first thing u should note is that we require (x-y)^4Veronica wrote:What is the value of (x-y)^4?
1. the product of x and y is 7
2. x and y are integers
Thanks!
which is as good as |x-y|
what essentially it means is that u can get value of x-y or y-x... the answer of (x-y)^4 will remain the same...
so basically if u boil down to 2 digits for x and y... the answer wud be sufficient... as it wont matter which number we assign to either..
statement 1
xy=7
there are infinite values of x and y and therefore many values of x-y
e.g
3.5 x 2 = 7
1 x 7 = 7
insufficient
statement 2
x & y are integers ... infinite values again...
insufficient
statements together...
we know xy=7
where 7 is prime... and x & y are integers...
so we have the following values for x&y
1,7
or
-1, -7
both will give u a constant value for (x-y)^4
hence sufficient...
IMO C
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tpr-becky
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This one looks harder than it is - it is just about numbers. if x(y)=7 then they could be 1 and 7 or .5 and 14 so we have no idea what (x-y)^4 could be. so BCE
if they are integers - that is not helpful in determining value. So CE
Together the only integers that have product of 7 are 1 and 7 or -1 and -7 which looks like it could work becuase (1-7)^4 is the same as (7-1)^4 due to the fact that even exponents take away the sign for a coefficient. becuase of the minus sign it doesn't matter whether the numbers are positive or negative. (-1--7) is the same as 7-1 -- for any of the answers the answer is either 6^4 or -6^4 which work out to be the same so teh answer is C.
if they are integers - that is not helpful in determining value. So CE
Together the only integers that have product of 7 are 1 and 7 or -1 and -7 which looks like it could work becuase (1-7)^4 is the same as (7-1)^4 due to the fact that even exponents take away the sign for a coefficient. becuase of the minus sign it doesn't matter whether the numbers are positive or negative. (-1--7) is the same as 7-1 -- for any of the answers the answer is either 6^4 or -6^4 which work out to be the same so teh answer is C.
Becky
Master GMAT Instructor
The Princeton Review
Irvine, CA
Master GMAT Instructor
The Princeton Review
Irvine, CA
