Question

                               x          x-1
Resolva a equação 7      + 7       = 8.
  x = -2

  x = -3

  x = 2

  x = 1

  x = 3

Answer 1

$\frac{x}{7}+\frac{x-1}{7}=8 \\ \\ x+x-1=56 \\ \\ 2x=57 \\ \\ x=\frac{57}{2}$

ou

$7^x+7^{x-1}=8 \\ \\ 7^x+\frac{7^x}{7}=8 \\ \\ y=7^x \\ \\ y+\frac{y}{7}=8 \\ \\ 7y+y=56 \\ \\ 8y=56 \\ \\ y=7 \\ \\ \therefore 7^x=7 \rightarrow x=1$

Answer 2

Olá.

$7^x+7^{x-1}= 8\\ 7^x+ 7^x . 7^{-1}=8 \\ 7^x+ \frac{7^x}{7}= 8\\ y= 7^x \\ 7y+y= 8.7\\ 8y= 56\\ y= \frac{56}{8} \\ \\ y=7 \\ 7^x= 7 \\ 7^x=7^1\\ \boxed{x= 1}$