For the entry in the second row, second column, we will do the same thing with the second row of the first matrix and the second column of the second matrix: In order to completely fill out this matrix, we would have to do 9 calculations, but don’t fret, the ACT is more likely to give you smaller matrices or matrices with more zeros or ask you to find just one entry in a matrix.
This means that we are multiplying a matrix by an ordinary number.
Every entry inside the matrix just gets multiplied by that number.
We add or subtract matrices by adding or subtracting the corresponding numbers (the numbers that are in the same “spot” on each matrix).
Notice that the size of the matrices is the same, and that each element in the first matrix is added to the corresponding element in the second matrix to get the corresponding element in the third matrix. With that understanding, we can solve for x by writing a simple equation: x 9 = 11; x = 2. You can only multiply matrices if the number of columns in first matrix equals the number of rows in the second matrix.