Given thatA=[1203]
Find elementary Matrices E1 and E2 such that E2 E1 A = I
Start by eliminating the 2 in matrix A.
E1A=[1003] [acbd][1203]=[1003] [a+2bc+2d3b3d]=[1003]
hence a=1; b= 0; c=-2 ; d= 1
Therefore E1 = [1−201] [Answer]
Find E2 (since we know what E1A is)
[acbd][1003]=[1001] [ac3b3d]=[1001]
hence a= 1; b= 0; c= 0; d=31
Therefore E2 = [10031] [Answer]
Comments