work done by the force F=3i^−j^−2k^ acting on a particle such that the particle is displaced from point A (- 3, 4, 1) to point B (- 1, - 1, - 2).

Here F→=3i^−j^−2k^AB→=P.V. of B−PV. of A=(−i^−j^−2k^)−(−3i^−4j^+k^)=2i^+3j^−3k^ Let s→=AB→ be the displacement vector  Now work done =F→⋅s→=(3i^−j^−2k^)⋅(2i^+3j^−3k^)=6−3+6=9