Question

3la puterea n-1 înmulțit cu 7 la puterea n+1 supra lui 21 la puterea n

Answer 1

   
[tex]\displaystyle \\ \frac{3^{n-1}\times 7^{n+1}}{21^n} =\\ \\ =\frac{3^{n-1}\times 7^{n-1+2}}{21^{n-1+1}} =\\ \\ =\frac{3^{n-1}\times 7^{n-1}\times 7^2}{21^{n-1}\times21^1} =\\ \\ =\frac{(3\times 7)^{n-1} \times 49}{21^{n-1}\times21} =\\ \\ =\frac{21^{n-1} \times 49}{21^{n-1}\times21} = \frac{49}{21}= \boxed{\frac{7}{3}}[/tex]