Chapter 7.2, Problem 2E

Compute the quadratic form X^TAX, when $A=\left[\begin{array}{ccc}3& 2& 0\\ 2& 2& 1\\ 0& 1& 0\end{array}\right]$ and

a. $x=\left[\begin{array}{c}{x}_1\\ x_2\\ x_3\end{array}\right]$ b. $x=\left[\begin{array}{c}-2\\ -1\\ 5\end{array}\right]$ c. $x=\left[\begin{array}{c}1/\sqrt{2}\\ 1/\sqrt{2}\\ 1/\sqrt{2}\end{array}\right]$