Vectors and matrices

Practice sheet

Fresh questions from the whole chapter, to do on paper.

To save a PDF, choose “Save as PDF” in the print dialog.

  1. The vector ⟨2,1⟩\langle 2, 1 \rangle starts at the point (1,1)(1, 1). Tap the point where it ends.
  2. P=(3,3)P = (3, 3) and Q=(8,8)Q = (8, 8). Which vector is PQ→\overrightarrow{PQ}?
    1. ⟨5,5⟩\langle 5, 5 \rangle
    2. ⟨−5,−5⟩\langle -5, -5 \rangle
    3. ⟨11,11⟩\langle 11, 11 \rangle
  3. A plane flies due east at 101 miles per hour through the air, and the wind blows due north at 32 miles per hour. Find its speed over the ground, to 1 decimal place.Not to scale
  4. Two people pull a box: one with 36 newtons due east, the other with 59 newtons due north. At what angle north of east does the box start to move? Give degrees to 1 decimal place.Not to scale
  5. Let A = (3−375)\begin{pmatrix} 3 & -3 \\ 7 & 5 \end{pmatrix} and B = (−4−4−55)\begin{pmatrix} -4 & -4 \\ -5 & 5 \end{pmatrix}. What is the entry in row 1, column 2 of A + B?
  6. Let A = (2062)\begin{pmatrix} 2 & 0 \\ 6 & 2 \end{pmatrix}. What is the entry in row 2, column 1 of 3A?
  7. A shop records sales in a matrix with one row for each of its 4 stores and one column for each of 7 days. What are the dimensions of the matrix?
    1. 4 × 7
    2. 7 × 4
    3. 28 × 1
  8. Let A = (423−2)\begin{pmatrix} 4 & 2 \\ 3 & -2 \end{pmatrix} and B = (7954)\begin{pmatrix} 7 & 9 \\ 5 & 4 \end{pmatrix}. What is the entry in row 1, column 1 of AB?
  9. Let A = (8884)\begin{pmatrix} 8 & 8 \\ 8 & 4 \end{pmatrix} and B = (2332)\begin{pmatrix} 2 & 3 \\ 3 & 2 \end{pmatrix}. What is the entry in row 2, column 1 of AB?
  10. A is a 2 × 5 matrix and B is a 5 × 8 matrix. What are the dimensions of AB?
    1. 2 × 8
    2. 5 × 5
    3. AB is not defined
  11. Let A = (9236)\begin{pmatrix} 9 & 2 \\ 3 & 6 \end{pmatrix}. What is the first component of A(−3−1)\begin{pmatrix} -3 \\ -1 \end{pmatrix}?
  12. The matrix (0−110)\begin{pmatrix} 0 & -1 \\ 1 & 0 \end{pmatrix} maps the point (8, 0) to (0, 8) and (0, 8) to (−8, 0). Which transformation does it represent?
    1. A rotation of 90° counterclockwise about the origin
    2. A reflection in the line y = x
    3. A rotation of 90° clockwise about the origin