Question

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$\sqrt{ {21}^{3} } = \sqrt{4 .10.8} =$
alguém sabe ?​

Answer 1

$\sf \sqrt{ {21}^{3} } = \sqrt{4 \times 10 \times 8} \\ \\\sf (21 ^{3} ) ^{ \frac{1}{2} } \sqrt{4 \times 10 \times 8 } \\ \\ (21 ^{3} ) ^{ \frac{1}{2} } \sqrt{320} \\ \\\sf 21 ^{ \frac{3}{2} } \times 8 \sqrt{5} \\ \\ 21 \sqrt{21} \times 8 \sqrt{5} \\ \\\sf 21 \times 8 \sqrt{21 \times 5} = \red{168 \sqrt{105}}$