Dimesions Of a Matrix

To find the dimensions of the matrix, you need to count how many columns and rows there are. 

The rows are the numbers going horizantally.

 

The columns are the numbers going vertically.

 For the example below, there are two rows and three columns. So the dimensions would be written 2 x 3. The dimension format will always be written ROW x COLUMN.

 For the matrix below, the dimensions are 3 x 3. This matrix would also be classified as a square matrix, since the number of rows and columns are the same.

The matrix below has the dimensions 3 x 3. This matrix is called an identity matrix, because the numbers going across the diagonal is 1.

Error Analysis

1)

The error in this equation is that the slope goes up by 2, not 10, so the equation should read y=2x+9

2)

The error with this system of equations is that the student should have plugged the solution into both  equations, not just one, to check and see if the point works for both problems.

3)

For the first inequality, the error is that the line should have been dotted, since the actual equation isn't included in the solution. For the second inequality, the solutions should have been shaded above the line, since the equation says "greater than or equal to".

4)

For the first inequality, the line should be dotted, again, since the actual equation isn't included in the solution. For the second inequality, the solutions should be shaded below the line since the equation reads "less than or equal too".