Linear Independence
1. **State the problem:** Prove that the vectors $\mathbf{u} = \langle 1, 1, 0 \rangle$, $\mathbf{v} = \langle 0, 1, 1 \rangle$, and $\mathbf{w} = \langle 1, 0, 1 \rangle$ are linearly independent.
2. **Recall the definition:** Vectors are linearly independent if the only solution to the equation
$$c_1 \mathbf{u} + c_2 \mathbf{v} + c_3 \mathbf{w} = \mathbf{0}$$
is $c_1 = c_2 = c_3 = 0$.
3. **Set up the equation:**
$$c_1 \langle 1, 1, 0 \rangle + c_2 \langle 0, 1, 1 \rangle + c_3 \langle 1, 0, 1 \rangle = \langle 0, 0, 0 \rangle$$
4. **Write component-wise equations:**
$$\begin{cases}
c_1 + 0 \cdot c_2 + c_3 = 0 \\
c_1 + c_2 + 0 \cdot c_3 = 0 \\
0 \cdot c_1 + c_2 + c_3 = 0
\end{cases}$$
5. **Simplify the system:**
$$\begin{cases}
c_1 + c_3 = 0 \\
c_1 + c_2 = 0 \\
c_2 + c_3 = 0
\end{cases}$$
6. **From the first equation:**
$$c_3 = -c_1$$
7. **From the second equation:**
$$c_2 = -c_1$$
8. **Substitute $c_2$ and $c_3$ into the third equation:**
$$(-c_1) + (-c_1) = 0 \implies -2c_1 = 0$$
9. **Solve for $c_1$:**
$$c_1 = 0$$
10. **Back-substitute to find $c_2$ and $c_3$:**
$$c_2 = -0 = 0, \quad c_3 = -0 = 0$$
11. **Conclusion:** The only solution is $c_1 = c_2 = c_3 = 0$, so the vectors $\mathbf{u}$, $\mathbf{v}$, and $\mathbf{w}$ are linearly independent.