Vectors, dot product and cross product. URGENT please Help

1) Vector v has magnitude 10 units, positive, and equal x and y components, and a z component of 4. Determine V.

2) vector u is give as u= (1, -2, 1)

a) determine 3 different non-collinear vectors perpindicular to u.

b) show that the 3 vectors in part a are coplanar

3) prove that (a-b)x(a+b) = 2(axb)

4) Find total work done by 15 N force, F, in the direction of the vector, (1,2,2) when it moves a particle from O(0,0,0) to P(1, -3, 4) and then from P to Q(7,2,5). The distance is measure in metres.