(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

Veronica 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!

first thing u should note is that we require (x-y)^4
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

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.