Final answer:
The order of the matrix [[5,1,-5],[5,-5,5],[1,5,5]] is 3x3 because it has three rows and three columns.
Step-by-step explanation:
The order of a matrix is determined by the number of rows and columns it contains. To find the order of the given matrix, we count the number of rows and the number of columns. The given matrix [[5,1,-5],[5,-5,5],[1,5,5]] has 3 rows and 3 columns. Therefore, the order of the matrix is 3x3.