Determinants
Let P and Q be 3 × 3 matrices with P ≠ Q. If P3= Q3 and P2Q = Q2P, then determinant of(P2+ Q2) is equal to
-2
1
0
-1
C.
P3= Q3P3– P2Q = Q3– Q2PP2(P – Q) = Q2(Q – P)P2(P – Q) + Q2(P – Q) = O(P2+ Q2)(P – Q) = O ⇒ |P2+ Q2| = 0
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