Question

Решите плз:
5*9^х+9^х-2=406

Answer 1

$5*9^x+9^{x-2}=406\\ \\ 5*9^x+\frac{9^x}{81} =406\\ \\ 5*81*9^x+9^x=406*81\\ \\ 405*9^x+9^x=406*81\\ \\ 406*9^x=406*81\\ \\ 9^x=81\\ \\ 9^x=9^2\\ \\ x=2$