Let A= bmatrix2&1&2\\6&2&11\\3&3&2 bmatrix and P= bmatrix1&2&0\\5&0&2\\7&1&5 bmatrix. The sum of the prime factors of |P-1AP-2I | is equal to
- 66
- 27
- 23
- 26
Answer
(4) 26
Solution
P-1AP-2I=P-1AP-2P-1P=P-1(A-2I)P
|XYZ|=|X||Y||Z| and |P-1||P|=1 required =|A-2I|
|A-2I|= vmatrix0&1&2\\6&0&11\\3&3&0 vmatrix=0-1(0-33)+2(18-0)=69
69=3 23 sum =3+23=26
Answer: (4)