Answer:
C. [tex]\sqrt{18}[/tex]
Step-by-step explanation:
[tex]\frac{4\pi }{\pi }[/tex] = 4(whole number)
[tex]\sqrt{ 6^{2}}[/tex] = 6(whole number)
[tex]\sqrt{18}[/tex] = 4.2426406871192851464050661726291(goes on and on)
21.989(terminating number)
Irrational numbers are un-whole numbers that do not terminate and cannot be turned into a fraction.
