Determine a vector which when added to the resultant of A→=2i^+5j^−k^ and B→=3i^−4j^−k^ gives unit vector along negative y direction.
−5i^−2j^+2k^
−5i^−j^+k^
−5i^−j^+2k^
5i^−j^+2k^
Let C→ is required vector, then C→+A→+B→=−j^⇒ C→+2i^+5j^−k^+3i^−4j^−k^=−j^⇒C→=−5i^−2j^+2k^