Most of the problems i understood, but this one was difficult for me:
Sin(arccos(x/3)+arcsin(x))
My answer was (x^2+(x^4-10x^2+9)^1/2)/3
in words, my answer is X squared times the square root of x to the fourth minus 10 x squared plus 9, all of that being divided by 3.
My answer just seems...