# The number of 3x3 non singular matrices, with four entries as 1 and all other entries are 0 ,is? a)5 b)6 c)at least 7 d) less than 4

##### 1 Answer

Dec 19, 2017

There are exactly

#### Explanation:

First consider the number of non-singular matrices with

They must have one

#((1, 0, 0), (0, 1, 0), (0, 0, 1))" "((1, 0, 0), (0, 0, 1), (0, 1, 0))" "((0, 1, 0), (1, 0, 0), (0, 0, 1))#

#((0, 1, 0), (0, 0, 1), (1, 0, 0))" "((0, 0, 1), (1, 0, 0), (0, 1, 0))" "((0, 0, 1), (0, 1, 0), (1, 0, 0))#

For each of these