Here's the question you clicked on:
nehakatyal
Find a vector in V^3 that is perpendicular to u (5,-2,3)
you need to find a vector V such that the dot product u (dot) V = 0; in other words: 5V1 - 2V2 + 3V3 = 0
for example if you set V1 = V2 = V3 = 0; that is one vector however its not interesting so you can take V3 =0 and that means that V2 = -5 , V1 = 2
So what would be the answer for V^3?