A Level Further Maths- FP1 Vector ProductWatch
Would the fact this vector has magnitude 5 not change anything and essentially is it asking you to just find the vector product to show its perpendicular to 4i+k and √ 2j +k or does the magnitude change the calculation.
I would find the vector perpendicular to those, without considering the magnitude first. Then find the magnitude of this vector and see what you have to multiply/divide the vector by the make the magnitude 5. Not the greatest explanation so lmk if it doesn't make sense