Integrate[Sin[x],x]

Integrate[Sin[3x],{x,0,Pi/2}]

Integrate[1/(y^3+1),{y,0,2},{x,0,y^2}]

Integrate[1/(y^3+1),{x,0,y^2}]

Integrate[1/(y^3+1),{x,0,4},{y,Sqrt[x],2}]

Integrate[1/(y^3+1),y]