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If  then what is  equal to?

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  1. Δ
  2. 7Δ
  3. 72Δ
  4. -72Δ

Answer (Detailed Solution Below)

Option 4 : -72Δ
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Detailed Solution

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Concept::

  • The interchange of any two rows (or columns) of the determinant changes its sign.
  • The determinant remains unaltered if its rows are changed into columns and the columns into rows.

 

Calculation:

C1 → C1 - 5C3, C2 → C2 - 7C3

 

Using the property of determinants

∴  A = -72Δ

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