3^(х+2 )+3^(х-1) -3^х=225

Question

3^(х+2 )+3^(х-1) -3^х=225

Answer 1

 3^x*3^2+3^x*1/3 -3^x=225
   9*3^x+1/3*3^x-3^x=225
 3^x(9+1/3-1)=225
 3^x* 25/3 =225
 3^x=225 : 25/3
 3^x=27
 3^x=3^3
 x=3