> F:=xi->6*(1-xi)*xi-1;

                     F := xi -> 6 (1 - xi) xi - 1

> Int(F(xi),xi=0..1)=int(F(xi),xi=0..1);

                       1
                      /
                     |
                     |   6 (1 - xi) xi - 1 dxi = 0
                     |
                    /
                      0

> G(xi):=(1-xi)*xi*(5*(1-xi)*xi-1);

               G(xi) := (1 - xi) xi (5 (1 - xi) xi - 1)

> Int(G(xi),xi=0..1)=int(G(xi),xi=0..1);

                1
               /
              |
              |   (1 - xi) xi (5 (1 - xi) xi - 1) dxi = 0
              |
             /
               0

> plot({F(xi),G(xi)},xi=0..1);

> 
