Question

ARATATI CA FRACTIA 4^n*5^N+1 +4^N+1 *5^N /3^N *7^N+1+3^N+1*7^N-21^N SE SIMPLIFICA PRIN 9 PT ORCE NR NAPARTINE N*

Answer 1

$\frac{4^{n}5^{n+1}+4^{n+1}5^{n} }{3^{n}7^{n+1}+3^{n+1}7^{n}-21^{n}} = \\ \\\frac{4^{n}5^{n}5+4^{1} 4^{n}5^{n} }{3^{n}7^{n}7+3^{n}3^{1} 7^{n}-21^{n}}= \\ \\\frac{ 20^{n}(5+4)}{21^{n}(7+3-1) } = \\ \\ = \frac{20^{n}9}{21^{n}9 }$
evident se simplifica prin 9