
Elementary Math Fractions, Percentages, Word Problems, Equations, Inequations, Factorization, Expansion 
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January 29th, 2018, 10:02 PM  #1 
Senior Member Joined: Apr 2008 Posts: 194 Thanks: 3  Why is choice 3 the answer?
(ex) Which of the following statements is true? (1) If P=Q, then P^n=Q^n where n is any integer (2) If P^n=Q^n, then P=Q where n is any integer (3) If P=Q, then P^n=Q^n where n is any positive integer (4) If P^n=Q^n, then P=Q where n is any positive integer my attempt If I let P and Q be 2 and let n be 1, these values satisfy all four choices. Next, I let P and Q be 2 and let n be 1. these values satisfy (1) and (2). So, I don't know why the answer key says (3) is the answer. Please help me. Thanks a lot. 
January 29th, 2018, 10:58 PM  #2 
Senior Member Joined: Sep 2015 From: USA Posts: 2,427 Thanks: 1314 
you can't prove anything by finding an example that works, you can only disprove something by finding an example that doesn't. (1) would be true except that 1/0 is undefined so that the statement isn't true when P=Q=0 when n is negative (2) isn't true for Q=P and n even (3) is true (4) is false for the same reason as (2) 
January 30th, 2018, 10:49 PM  #3 
Senior Member Joined: Apr 2008 Posts: 194 Thanks: 3 
Thank you very much again, romsek.


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