1. The problem statement, all variables and given/known data a particle with a charge of -1.24 x 10^-8 c is moving with instantaneous velocity v= 4.19 x 10^4 i + -3.85 x 10^4 j (both in m/s). what is the force exerted on this particle by a magnetic field a) 1.4 T i and b) 1.4 T k ? 2. Relevant equations F = qv x B (cross product not multiplication) 3. The attempt at a solution I tried using a determinate for part a where you put i j k and the velocity vector multiplied by q and then the magnetic field vector underneath that but i got -6.68 x 10^-4 i, however the books answers says that it is in the -k direction. I don't understand the way my physics teacher does the cross multiplication that's why i tried using a determinate like in calculus....please help?!?!