數學功課(vector) Please help me!!!

Please step by step!!!!!

1) The work done by a force vector F in moving a body through a displacement vector r is given by vector F點 vector r. A force vector F=3i+7k causes a body to move from one point with coordinates (1,1,2) to another
point ( 7,3,5).

a) Find the displacement, vector r, of the body.

b)Find the work done by the force.



2) Find the unit vector which is peroendicular to both of the vector i+2j+7k and i+j+2k