Which one, with integer coefficients, is the quartic equation whose roots are: $\pm \sqrt{8+\sqrt{13}}$.
The verbal 4th-degree equation, whose roots are

$$
\begin{gathered}
\sqrt{8+\sqrt{13}}, \sqrt{8-\sqrt{13}},-\sqrt{8+\sqrt{13}},-\sqrt{8-\sqrt{13}}, \\
(x-\sqrt{8+\sqrt{13}})(x-\sqrt{8-\sqrt{13}})(x+\sqrt{8+\sqrt{13}})(x+\sqrt{8-\sqrt{13}})=0
\end{gathered}
$$

can be written in the form. If we multiply the first and third, and the second and fourth factors on the left side, we get:

$$
\left(x^{2}-8-\sqrt{13}\right)\left(x^{2}-8+\sqrt{13}\right)=0
$$

or

$$
\left(x^{2}-8\right)^{2}-13=0 \text { or } x^{4}-16 x^{2}+51=0
$$

József Fülöp (Bencés g. V. o., Győr)