I'll do the first one......the other two should then be easy
projection of u = ( 2,4,2) onto v = (1,2,1)
Calculate the dot product of the two vectors =
2*1 + 4*2 + 2*1 = 2 + 8 + 2 = 12
Calculate the length of the vector v = sqrt [ 1^2 + 2^2 + 1^2 ] = sqrt [ 6]
Square this = 6
So
dot product of u * v
projv u = __________________ * vector v =
( length of v )^2
12
____ * ( 1,2,1) =
6
2 * (1,2,1) =
(2, 4 , 2 )