Step-by-step explanation:
from the second:
A=[3 -1]. -2B
[-5 0]
input this into 1
2([3 -1]) -(2B) -B =[1 3]
([-5 0]). [0 5]
[6 -2] -4B-B=[1 3]
[-10 0]. [0 5]
-5B=[1 3] -[3 -1]
[0 5]. [-5 0]
-5B= [1-3 3+1]
[0+5 5+0]
B= [-2/5 4/5]
[1 1]
A=[(19/5) (3/5)]
[-3. 2]
using the formula I derived
that's how I got A
