SOLUTION: Can someone show me how to write the rational expression in lowest terms? r-13/13-r

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Question 76828: Can someone show me how to write the rational expression in lowest terms?
r-13/13-r
Answer by bucky(2189) About Me  (Show Source):
You can put this solution on YOUR website!
My interpretation of your problem is that you need to simplify the rational
expression:
.
%28r-13%29%2F%2813-r%29
.
That being the case, notice what happens if you change the denominator by factoring
out -1. If you do that factoring you get:
.
%28r-13%29%2F%28%28-1%29%2A%28-13%2Br%29%29
.
and re-arranging the terms inside the parentheses in the denominator results in:
.
%28r-13%29%2F%28%28-1%29%2A%28r-13%29%29
.
Now you can cancel the like terms of the denominator and numerator to get:
.
cross%28r-13%29%2F%28%28-1%29%2Across%28r-13%29%29
.
and this leaves you with just:
.
1%2F%28-1%29
.
So the result of this simplification is just plain -1
.
Hope this helps you to see your way through the problem.
.