NIMCET 2011 — Mathematics PYQ
NIMCET | Mathematics | 2011If A and B are two square matrices such that B=−A−1BA, then (A+B)2 will be equal to:
Choose the correct answer:
- A.
0
- B.
A2+2AB+B2
- C.
A2+B2
A2+B2
Explanation
1. Simplify the given condition:
Given:
Multiply both sides by A from the left:
Since AA−1=I (Identity matrix):
2. Rearrange the relation:
3. Expand the required expression:
We need to find the value of (A+B)2. For matrices, the expansion is:
4. Substitute the condition from Step 2:
Substitute AB+BA=0 into the expansion:
Conclusion:
The expression simplifies to A2+B2.
The correct option is (c).
Explanation
1. Simplify the given condition:
Given:
Multiply both sides by A from the left:
Since AA−1=I (Identity matrix):
2. Rearrange the relation:
3. Expand the required expression:
We need to find the value of (A+B)2. For matrices, the expansion is:
4. Substitute the condition from Step 2:
Substitute AB+BA=0 into the expansion:
Conclusion:
The expression simplifies to A2+B2.
The correct option is (c).
