if a, b, c, d, e, and f are all integers prove that r is rational

$\displaystyle r = [(a/b) - (e/f)] / c/d$

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- Mar 2nd 2010, 04:52 PMMathwizard4Is this rational and why?
if a, b, c, d, e, and f are all integers prove that r is rational

$\displaystyle r = [(a/b) - (e/f)] / c/d$ - Mar 2nd 2010, 04:58 PMDrexel28
- Mar 2nd 2010, 05:08 PMMathwizard4
- Mar 3rd 2010, 02:42 AMemakarov
First, you need to make sure that you never divide by 0.

Second, all integers are rational, and rational numbers are closed under addition, subtraction, multiplication and division by a non-zero (i.e., the result of the operation is again rational).