# Questions in Section Linear Algebra

Find the unit vector in the direction of `v=(3, -4, 12)`.

Find the distance between the points `(8,4)` and `(0,19)`.

The angle between the vectors `u=<1,2>` and `v=<4,-1>` to the nearest tenth of a degree.

Find the reduced row echelon form of this augmented matrix: `[[13,3,-1,300],[3,1,0,100],[-6,-1,1,350]]`

Find the angle `theta` between `bbv=-3i+4j` and `bbw=5i+12j`. If necessary, round to the nearest tenth of a degree.

Consider the matrix `B=[[2,0],[0,-1]]`

- Find the characteristic polynomial of B
- Find the eigenvalues of B
- Find the associated eigenvectors of B

Solve the following system of linear equations by inverting the coefficient matrix:

`3x_1+5x_2=b_1`

`x_1+2x_2=b_2`

Write a 4x4 matrix `A=[a_(ij)]`, whose entries satisfy the following conditions:

- `a_(ij)=i^(j-1)`
- `a_(ij)={(1 if | i-j | > 1),(-1 if | i-j | <= 1):}`

Solve the following system of linear equations by Gauss-Jordan elimination method:

`x_1+x_2+2x_3=8`

`-x_1-2x_2+3x_3=1`

`3x_1-7x_2+4x_3=10`

Write the definition of a reduced row echelon form matrix. Write which of the following matrices are in the row-echelon and which are in the reduced row-echelon forms:

- `[[1,0,0],[0,0,0],[0,0,1]]`
- `[[0,1,0],[1,0,0],[0,0,0]]`
- `[[1,1,0],[0,1,0],[0,0,1]]`
- `[[1,0,2],[0,1,3],[0,0,0]]`