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Write the Value of √ − 25 × √ − 9 .

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Question

Write the value of \[\sqrt{- 25} \times \sqrt{- 9}\].

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Solution

\[\sqrt{- 25} \times \sqrt{- 9} = 5\sqrt{- 1} \times 3\sqrt{- 1}\]

                          \[ = 5i \times 3i\]

                          \[ = 15 i^2 \]

                          \[ = - 15\]

Hence, 

\[\sqrt{- 25} \times \sqrt{- 9} = - 15\]

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Chapter 13: Complex Numbers - Exercise 13.5 [Page 63]

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R.D. Sharma Mathematics [English] Class 11
Chapter 13 Complex Numbers
Exercise 13.5 | Q 15 | Page 63

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