Linear independence of vectors $w_1,w_2,w_3$ Suppose that $S = \{v_1,v_2,v_3\}$ is a linearly independent set of vectors in a vector space $V$.
Is $T = \{w_1,w_2,w_3\}$, where $w_1 = v_1 + v_2$, $w_2 = v_1 + v_3$, $w_3 = v_2 + v_3$, linearly dependent or
linearly independent? Why?
Am I right in claiming that vector space $V$ is a subset of $T$? 
Do I set the linear combinations of $w_1$, $w_2$, $w_3$ equal to zero?
$$
c_1(v_1+v_2) + c_2(v_1+v_3) + c_3(v_2+v_3) = 0
$$
and then solve for $c_1,c_2,c_3$ and see if they have unique solutions?

*

*No, $V$ is not a subset of $T$: how can it be? 

*Yes, the strategy for showing linear independence is correct. What can you do next, in order to use the hypothesis on $\{v_1,v_2,v_3\}$? Write
$$
(c_1+c_2)v_1+(c_1+c_3)v_2+(c_2+c_3)v_3=0
$$
and then you know that …
