Consider terms built from elements of $\mathbb Q$ and the operations $+,\times,-,/$, and $\sqrt[n]{\,\cdot\,}$ for each natural number $n$. Given the promise that two terms are well-formed -- that is, there is no division by zero, and no even roots of negative numbers -- is there an algorithm which decides when the two terms are equal?
A related question was posted herehere, but it is more general (as it allows arbitrary exponentiation, rather than just by rational numbers).