1. The problem statement, all variables and given/known data use triple integral to find the volume of tetrahedron enclosed by the coordinat planes "x=o , y=0 , z=0" and the plane 2x+y+z=0 2. Relevant equations 3. The attempt at a solution I will integrate the constant function f(x,y,z)=1 by the order : dzdydx the equation will be : z=-2x-y so the limits for the inner integral will be from 0 to -2x-y when z=0 ---> y=-2x so the limits for the middle integral will be from 0 to -2x THE PROBLEM HERE IS THAT when z=0,y=0 ---> x=0 .. !!!! so the limits for the outer integral will be from 0 to 0 .. !! and this means the triple integral will be 0 .. !! so there is no volume ??!