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AP EAMCET · Maths · Matrices

If \(P\) is a square matrix with \(P^2=P\) and if \(I\) is the unit matrix of the same order as of \(P\) then \((P+I)^4=\)

  1. A \(I+9 P\)
  2. B \(I+11 P\)
  3. C \(I+13 P\)
  4. D \(I+15 P\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(I+15 P\)

Step-by-step Solution

Detailed explanation

\((P+I)^2 = P^2+PI+IP+I^2 = P+P+P+I = 3P+I\) \((P+I)^4 = ((P+I)^2)^2 = (3P+I)^2\) \((3P+I)^2 = (3P)^2+3PI+I(3P)+I^2 = 9P^2+3P+3P+I\) \(= 9P+6P+I = 15P+I\)