I am using the EqualComAss test. Is there a possibility to recognize negative powers as inverses of positive powers (e.g. \(x^{-6}\) as \(1/x^6\)) and \(\sqrt{x}\) as \(x^{1/2}\) without having to set both of them as a correct answer in the prt?

### STACK - rational and negative powers

Number of replies: 2
Hello,

I am using the EqualComAss test. Is there a possibility to recognize negative powers as inverses of positive powers (e.g. \(x^{-6}\) as \(1/x^6\)) and \(\sqrt{x}\) as \(x^{1/2}\) without having to set both of them as a correct answer in the prt?

I am using the EqualComAss test. Is there a possibility to recognize negative powers as inverses of positive powers (e.g. \(x^{-6}\) as \(1/x^6\)) and \(\sqrt{x}\) as \(x^{1/2}\) without having to set both of them as a correct answer in the prt?

### Re: STACK - rational and negative powers

Martin,

There isn't currently a mechanism to build arbitrary equivalence classes by choose subsets of the algebra rules, so I'm sorry but we don't have a test just for that. I can understand why it would be useful though!

Chris

### Re: STACK - rational and negative powers

Thanks for your answer. Is this feature planned in future versions?

Connected to the question about rational powers: If I put the term \(\frac{a \cdot b-a \cdot\sqrt{a}+b \cdot\sqrt{b}-\sqrt{a \cdot b}}{b^2-a}\) in the prt, STACK evaluates the same term as answer as wrong, while it returns \(\frac{a \cdot b-a^{3/2}+b^{3/2}-\sqrt{a \cdot b}}{b^2-a}\) as correct. How can I tell STACK that the term \(\frac{a \cdot b-a \cdot\sqrt{a}+b \cdot\sqrt{b}-\sqrt{a \cdot b}}{b^2-a}\) should also be correct?

Best,

Martin