Determine the pivot entries of the matrix

Question

A=(1 1 2 2 2

      1 2 1 3 2

      1 2 1 4 3

      1 3 0 4 2)

 

Determine the pivot entries of the matrix and use this to decide if the columns of A span R⁴

 

Answer 1

The best practice is to pick the biggest numbers in each column for the pivot.

So 1,3,2,4,3

 

BUT you have 5 columns so only four of them are needed to span.

 

It turns out that you do not need the last column. The online rref calculator I gave you 

returns the identity matrix when the last column is eliminated.

 

http://www.math.odu.edu/~bogacki/cgi-bin/lat.cgi?c=rref