How do you find the inverse of A=((1, 1, -1), (0, 1, 0), (1, 0, 1))?

1 Answer
Dec 16, 2016

=>A^(-1) = ((1/2,-1/2,1/2),(0,1,0),(-1/2,1/2,1/2))

Explanation:

Write as:

((1,1,-1,"|",1,0,0),(0,1,0,"|",0,1,0),(1,0,1,"|",0,0,1))
" "R_1-R_2
" "R_1-R_3
" "darr

((0,0,-2,"|",1,-1,-1),(0,1,0,"|",0,1,0),(1,0,1,"|",0,0,1))
" "R_1-:(-2)
" "darr

((0,0,1,"|",-1/2,1/2,1/2),(0,1,0,"|",0,1,0),(1,0,1,"|",0,0,1))
" "R_3-R_1
" "darr

((0,0,1,"|",-1/2,1/2,1/2),(0,1,0,"|",0,1,0),(1,0,0,"|",1/2,-1/2,1/2))
" Swap "R_3" with "R_1
" "darr

((1,0,0,"|",1/2,-1/2,1/2),(0,1,0,"|",0,1,0),(0,0,1,"|",-1/2,1/2,1/2))

color(white)(.)

=>A^(-1) = ((1/2,-1/2,1/2),(0,1,0),(-1/2,1/2,1/2))