Dear NotGoodAtMath94,
Your multiplication of matrices is incorrect. The correct one is,
* =
Hope this will help you.
Think of a matrix multiplication as a series of "dot products". The number at the "i,j" place in the product AB is the dot product of the ith row of A and the jth column of B.
In your example, row 1 of A is (a, b, c) and column 1 of B is (e, h, k). The "dot product" of those is ae+ bh+ ck so your first number in the first column is ae+ by+ ck, not ae+ ah+ ak where you have multiplied the first column by a only.
In this case, since A has only one row, the product has only one row.