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K^2 - t^2

Expert replies
Source: — Problem Solving |

by ssmiles08 » Tue May 26, 2009 6:56 am
The only way the Sum/difference can be odd is if E + O = O or E - O = O

sincs E^2 = E and O^2 = O

Choice 1: E + O = O; So this rules out the first possibility

Choice 2: E + E (2 times any number is E) + O = O; So this rules out the second possibility

Choice 3: E + O = O; Same as the first choice so this rules out the third possibility as well.

So the answer left is (A)
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by gmat740 » Tue May 26, 2009 12:32 pm
Plug in k=3 and t=2

both k and t are integers and both satisfy the condition

k^2 -t^2 = 9 - 4 = 5(odd integer)

So we find that none of the conditions are full-filled.

So answer none.
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