[题目]求下列函数的偏导数:-|||-(1) =(x)^3y-(y)^3x;-|||-(2) =dfrac ({u)^2+(v)^2}(uv);-|||-(3) =sqrt (ln (xy));-|||-(4) =sin (xy)+(cos )^2(xy);-|||-(5) =ln tan dfrac (x)(y);-|||-(6) =((1+xy))^y;-|||-(7) =(x)^dfrac (y{2)};-|||-(8) =arctan ((x-y))^2.