1) If A and B are matrices and B= ABA-1 then the value of (A+B) (A-B) is A) A2+B2 B) A2−B2 C) A+B D) A-B Answer: Option BExplanation: B= ABA-1(Given) But B= BAA-A ∴ ABA−1=BAA−1⇒AB=BA Now (A+B)(A−B)=A2−AB+BA−B2 A2−AB+BA−B2[∵AB=BA] = A2−B2