[tex]\bf 21^{16}\cdot 4^{8}= \big(3\cdot7\big)^{16}\cdot \big(2^{2} \big)^{8}=[/tex]
[tex]\bf 3^{16}\cdot7^{16}\cdot 2^{2\cdot8}= 3^{16}\cdot7^{16}\cdot 2^{16}=\big(3\cdot7\cdot 2\big)^{16}=\red{\boxed{\bf 42^{16}}}[/tex]
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[tex]\bf 8^{3}\cdot 6^{9}= \big(2^{3} \big)^{3}\cdot \big(2\cdot3\big)^{9} =2^{3\cdot 3}\cdot 2^{9}\cdot3^{9} =[/tex]
[tex]\bf 2^{9}\cdot 2^{9}\cdot3^{9} = \big(2 \cdot 2\cdot3\big)^{9} =\blue{\boxed{\bf 12^{9}}}[/tex]
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#copaceibrainly
