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Question

Question: Matrix M<sub>r</sub> is defined as M<sub>r</sub> =\(egin{bmatrix} r & r–1 \ r–1 & r \\end{bmatrix}\...

Matrix Mr is defined as Mr =egin{bmatrix} r & r–1 \ r–1 & r \\end{bmatrix}, r Ī N. Then det. (M1) + det.(M2) + ........... + det.(M2009) = ?

A

2009

B

(2009)2

C

(2009)3

D

None of these

Answer

(2009)2

Explanation

Solution

det.(Mr) = r2 – (r –1)2 = 2r –1

r=12009(2r1)\sum_{r = 1}^{2009}{(2r–1)} = 2 × (2009×20102)\left( \frac{2009 \times 2010}{2} \right) – 2009

= (2009) × (2009) = (2009)2