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Evaluate $a^3 - \dfrac{1}{a^3}$ if $a - \dfrac{1}{a} = 0$.

 Jul 10, 2024
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first, let's focus in the equation we are given. 

Squaring both sides of the equation, we get that

(a2+2+1/a2)=0

 

This means that we have a2+1/a2=2

 

Now, let's focus on what we are trying to find. 

Let's notice that 

a31/a3=(a1/a)(a2+1+1/a2)

 

Wait a minute! we already have all the terms needed. We know both values to solve the problem. 

Since the first term is 0, we just have (0)(1)=0

 

So 0 is our answer. 

 

Thanks! :)

 Jul 10, 2024

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