Answer:
V = x³ + 9x² + 27x + 27
Step-by-step explanation:
The volume (V) of the tank is calculated as
aV = s³ ( s is the side length )
V = (x + 3)³
= (x + 3)(x + 3)(x + 3) ← expand 2nd/3rd factors using FOIL
= (x + 3)(x² + 6x + 9) ← distribute
= x³ + 6x² + 9x + 3x² + 18x + 27 ← collect like terms
= x³ + 9x² + 27x + 27
