Answer:
216 x^3 - 540 x^2 + 450 x - 125 = (6 x - 5)^3
Step-by-step explanation:
The first one cannot be a perfect cube, since the first term contains x^2 and not x^3.
the second one is not a perfect square (the coefficient of the middle term should be an even number: "-90")
The third expression is the perfect cube as shown.
