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Evaluate: 3 √ 96 × 3 √ 144 - Mathematics

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Question

Evaluate:

\[\sqrt[3]{96} \times \sqrt[3]{144}\]

Sum

Solution

96 and 122 are not perfect cubes; therefore, we use the following property:

\[\sqrt[3]{ab} = \sqrt[3]{a} \times \sqrt[3]{b}\] for any two integers a and b

\[\therefore \sqrt[3]{96} \times \sqrt[3]{144}\]

\[ = \sqrt[3]{96 \times 144}\]

\[= \sqrt[3]{\left( 2 \times 2 \times 2 \times 2 \times 2 \times 3 \right) \times \left( 2 \times 2 \times 2 \times 2 \times 3 \times 3 \right)}\]  (By prime factorisation)

\[= \sqrt[3]{\left\{ 2 \times 2 \times 2 \right\} \times \left\{ 2 \times 2 \times 2 \right\} \times \left\{ 2 \times 2 \times 2 \right\} \times \left\{ 3 \times 3 \times 3 \right\}}\]

\[ = 2 \times 2 \times 2 \times 3\]

\[ = 24\]

Thus, the answer is 24.

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Chapter 4: Cubes and Cube Roots - Exercise 4.4 [Page 31]

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RD Sharma Mathematics [English] Class 8
Chapter 4 Cubes and Cube Roots
Exercise 4.4 | Q 13.2 | Page 31

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