Given the equation:
[2312]A[−352−3]=[1001]
Let P=[2312], Q=[−352−3], and I=[1001]
The equation becomes: PAQ=I
To isolate A, multiply both sides on the left by P−1 and on the right by Q−1:
P−1(PAQ)Q−1=P−1IQ−1
A=P−1Q−1
For matrix P=[2312]:
det(P)=(2)(2)−(1)(3)
=4−3
=1
Using the inverse formula for a 2×2 matrix:
P−1=11[2−3−12]
=[2−3−12]
For matrix Q=[−352−3]:
det(Q)=(−3)(−3)−(2)(5)
=9−10
=−1
Q−1=−11[−3−5−2−3]
=[3523]
A=P−1Q−1
=[2−3−12][3523]
First row, first column: (2)(3)+(−1)(5)=6−5=1
First row, second column: (2)(2)+(−1)(3)=4−3=1
Second row, first column: (−3)(3)+(2)(5)=−9+10=1
Second row, second column: (−3)(2)+(2)(3)=−6+6=0
A=[1110]