Irrational numbers usually possess an unending decimal. Irrational numbers cannot be expressed as a fraction for example x/y where y is not equal to 0. Example of irrational numbers are
![\begin{gathered} \sqrt[]{2} \\ \pi \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/vrzp3toz9nkbodrcrfu56y6l14uwd9itjw.png)
The only number that is not an irrational number from the option is
![\sqrt[]{4}](https://img.qammunity.org/2023/formulas/mathematics/college/p9l00k7psrx39yddryfwrcimtusmj1c2yf.png)