order from least to greatest:
$\sqrt{21}$, $\sqrt[3]{27}$, $-\sqrt{64}$, $\sqrt[4]{25}$, $\sqrt{40}$, $-\sqrt[3]{81}$
\($\sqrt{21}$, $\sqrt[3]{27}$, $-\sqrt{64}$, $\sqrt[4]{25}$, $\sqrt{40}$, $-\sqrt[3]{81}$ \)
sqrt (21) = (4. and some decimal)
cube root 27 = 3
-sqrt (64) = -8
4th root of 25 = (5^2)^(1/4) = 5^(1/2) = sqrt 5 = ( 2. and some decimal)
sqrt 40 = 6.and some decimal
-cube root of 81 = ( -4. and some decimal )
You should be able to do this, now