SOLUTION: Evaluate: 3^-1-6^-1

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Question 625717: Evaluate: 3^-1-6^-1
Found 2 solutions by Alan3354, sanadei:
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
Evaluate: 3^-1-6^-1
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= 3%5E-1%2F1+-+6%5E-1%2F1
For 3^-1, multiply NUM & DEN by 3^1
= %283%5E-1%2A3%5E1%29%2F3%5E1+-+6%5E-1%2F1
= %283%5E0%29%2F3%5E1+-+6%5E-1%2F1
3^0 = 1
= 1%2F3%5E1+-+6%5E-1%2F1
= 1%2F3+-+6%5E-1%2F1
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Notice that the sign of the exponent changes, and it moves from NUM to DEN.
The vice versa is also true.
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Doing the same for 6^-1,
= 1%2F3+-+1%2F6
= 1/6

Answer by sanadei(3) About Me  (Show Source):
You can put this solution on YOUR website!
3^-1 =1/3
6^-1 =1/6 (since a^-1=1/a:law of indicis)
:- 1/3 - 1/6 =1/6.