[tex] \sqrt{25} [/tex] = 5 (perfect square ⇒ rational)
[tex] \sqrt{225} [/tex] = 15 (perfect square ⇒ rational)
[tex] \sqrt{78} [/tex] = 8.831760866 (irrational)
[tex] \sqrt{59} [/tex] = 7.681145748 (irrational)
A rational number can be expressed in the way a : b or [tex] \frac{a}{b} [/tex]
An irrational number cannot be expressed this way!
The two attachments are just worth looking at