Let S={M=[aij],aij∈{0,1,2},1≤i,j≤2} be a sample space and A={M∈S:M is invertible} be an event. Then P(A) is equal to [2023]
(1)
Let M=[pqrs] where p,q,r,s∈{0,1,2}
n(S)=34=81
First, we find p(A¯)
A¯={M∈S:|M|=0}
|M|=0⇒ps=qr
ps=qr=0⇒number of (p,q,r,s)=(32-22)2=25
ps=qr=1⇒number of (p,q,r,s)=12=1
ps=qr=2⇒number of (p,q,r,s)=22=4
ps=qr=4⇒number of (p,q,r,s)=12=1
P(A¯)=3181⇒P(A)=5081