It depends on whether it is the √(3)(x) or it is √(3x) is the x under the root or not?
If the x is NOT under the root and is separate you can do
∫0√(3)(π(3x2-x4)dx=6.5297 (rounded to 4 decimal places, you rounded to two 6.53)
If the x is under the root
∫01.44224957(π(3x-x4)dx=5.8813 (this is the first answer you got but you rounded to 3 decimal places)