In general, when solving a radical equation, you should first isolate the radical and the both sides.
a. square
b. subtract
c. multiply
d. add

The correct answer among the choices given is option A. In general, when solving a radical equation, you should first isolate the radical and then square both sides. Radical equations are expressions that contain a radical sign or a radix. For instace, 5 = √x.

 5 = √x
 (5)² = (√x)²
x = 25

Optio A. Square both sides to eliminate the radical.

The volume is 2212m cubed