well, there're some procedures.

for the first one, we have vectors on and you have three, so we have a linearly dependent set. One way to figure who's the bad guy (the dependent vector) is you to put them all into a matrix, like this:

now do elementary operations to reduce that matrix into row echelon form. (You'll see that the third row will become into zeros, and that shows the vector who makes your set linearly dependent.) Also note that the sum of the two first vectors yields the third one.

for the second one, put it into a matrix two and compute its determinant. It suffices to show it's not zero to see the linear independence. (Actually, when working on and having vectors, the determinant is the fastest way.)

finally, the third one, put'em into a matrix and reduce it into the row echelon form.