Let $\mathbb{R}^n$ be equipped with the inner product $\langle\mathbf{v}, \mathbf{w}\rangle=\mathbf{v}^T K \mathbf{w}$. Let $L[\mathbf{v}]=\mathbf{r} \mathbf{v}$ where $\mathbf{r}$ is a row vector of size $1 \times n$. (a) Find a formula for the column vector a such that (7.12) holds for the linear function $L: \mathbb{R}^n \rightarrow \mathbb{R}$. (b) Illustrate your result when $\mathbf{r}=(2,-1)$, using (i) the dot product (ii) the weighted inner product $\langle\mathbf{v}, \mathbf{w}\rangle=3 v_1 w_1+2 v_2 w_2$, (iii) the inner product induced by $K=\left(\begin{array}{rr}2 & -1 \\ -1 & 3\end{array}\right)$.