Posted by Donny on .
2 forces F1 = 2i3j and F2 = 3i + 12j are applied at a point. What force F must be applied at the point to counteract the resultant of these 2 forces?

calculus 
bobpursley,
R=F1+F2
F=R=F1F2=2i+3j3i12j combine terms.