Question

Daca 3 la puterea x + 3 la puterea -x =10 , atunci 9 la puterea x plus 9 la puterea -x =?

Answer 1

5^n+5^(n-1)+5^(n-2)=12²+3²+2¹
5^n+5^nx5⁻¹+5^n+5⁻²=144+9+2
5^n+5^n/5+5^n/25-155
5^n(1+1/5+1/25)=155
5^nx[(25+5+1)/25]=155
5^nx31/25=155
5^nx31=155x25
5^nx31=3875
5^n=3875:31
5^n=125
5^n=5³
n=3