integrate from upper 4 to lower 6 (yes, upper is less than the lower in this case) (3x - ((x^3)/4) ...

i tried splitting up the integrals and subtracting one from the other, but don't know the antiderivative of (x^3)/4 ...

am i going about this all wrong???

oops! copied the problem wrong lol. bounds are upper four to lower 0. my bad, please help.