Q1: Let $A \in \mathbb{R}^{3 \times 3}$ be a square matrix with $$ A = \begin{pmatrix} 2 & 4 & 7 \ 0 & 4 & 8 \ 0 & 0 & 2 \end{pmatrix} $$ What is the spectrum of $A$?

A1: ${ 2, 4 }$

A2: ${1, 2, 4 }$

A3: ${2, 4, 8 }$

A4: ${2, 4, 7, 8 }$

Q2: Let $A \in \mathbb{R}^{5 \times 5}$ be a square matrix with $$ A = \begin{pmatrix} 2 & 0 & 0 & 0 & 0 \ 7 & 5 & 0 & 0 & 0 \2 & 1 & 1 & 5 & 3 \ 6 & 1 & 0 & 7 & 3 \ 4 & 3 & 0 & 0 & 2 \end{pmatrix} $$ What is the spectrum of $A$?

A1: ${1, 2, 5, 7 }$

A2: ${1, 2, 5, 6 }$

A3: ${1, 2, 4, 5, 6, 7 }$

A4: ${1, 2, 3, 5, 7 }$