# Question 3, Exercise 2.1

Solutions of Question 3 of Exercise 2.1 of Unit 02: Matrices and Determinants. This is unit of Model Textbook of Mathematics for Class XI published by National Book Foundation (NBF) as Federal Textbook Board, Islamabad, Pakistan.

Identify the diagonal matrix, scalar matrix, identity matrix, lower triangular matrix, upper triangular matrix. $$A=\begin{bmatrix} 3 & 0 & 0 \\ 0 & 1 & 0 \\ 2 & 6 & 0 \end{bmatrix}$$ $$B=\begin{bmatrix} -6 & 0 & 0 \\ 0 & -6 & 0 \\ 0 & 0 & -6 \end{bmatrix}$$ $$C=\begin{bmatrix} 1 & 0 \\ 2 & 0 \end{bmatrix}$$ $$D=\begin{bmatrix} 1 & 0 & 0 \\ 0 & 1 & 0 \\ 0 & 0 & 1 \end{bmatrix}$$ $$E=\begin{bmatrix} 2 & 0 & 0 \\ 0 & 3 & 0 \\ 0 & 0 & 0 \end{bmatrix}$$ $$F=\begin{bmatrix} \sqrt{3} & 1 & 2 \\ 0 & 0 & 6 \\ 0 & 0 & 1 \end{bmatrix}$$ $$G=\begin{bmatrix} 1 & 0 & 0 \\ 0 & 0 & 0 \\ 0 & 0 & 0 \end{bmatrix}$$ $$H=\begin{bmatrix} 2 & 0 \\ 0 & 2 \end{bmatrix}$$

Solution. A: Lower triangular matrix
B: Scalar matrix; Diagonal matrix
C: Lower triangular matrix
D: Identity matrix; Scalar matrix; Diagonal matrix
E: Diagonal matrix
F: Upper triangular matrix
G: Diagonal matrix
H: Scalar matrix; Diagonal matrix