Question

4 si 6 va roooog mult

Answer 1

   
[tex]\displaystyle\\ 4)\\ (3^{21}+3^{20}+3^{19}):39=\\\\ =(3^{18+3}+3^{18+2}+3^{18+1}):39=\\\\ =(3^{18}\times3^3+3^{18}\times3^2+3^{18}\times3^1):39=\\\\ =3^{18}(3^3+3^2+3^1):39 =\\\\ =3^{18}(27+9+3):39 =\\\\ =3^{18} \times 39:39 = 3^{18}=3^{9\times2}=\boxed{\bf \Big(3^9\Big)^2 = pp}\\\\\\ 6)\\ 7^x + 7^{x+2}=2450\\\\ 7^x + 7^x\cdot 7^2=2450\\\\ 7^x(1+ 7^2)=2450\\\\ 7^x(1+ 49)=2450\\\\ 7^x \cdot 50 = 2450\\\\ 7^x = \frac{2450}{50}\\\\ 7^x = 49\\\\ 7^x = 7^2\\\\ \boxed{\bf x = 2} [/tex]