Question

Resolva as duas equações

Answer 1

$[ 1 ]$ $3 ^{x-2} + 3^{x+1}=84 ⇒ 3^{x}(3^{-2}+3^{1})=84$ ⇒$3^{x}= \frac{84}{  \frac{1}{9}+3 } ⇒ 3^{x}= \frac{84}{ \frac{28}{9}}⇒ 3^{x}= 9X\frac{84}{29}⇒ 3^{x}= \frac{756}{28} ⇒ 3^{x}=27⇒ 3^{x}=3^{3}⇒x=3$

$[ 2 ]$ $2^x+2^{x+1}=12 ⇒ 2^{x}(1+2^}-1})=12 ⇒ 2^{x}= \frac{12}{1+\frac{1}{2}} ⇒ 2^x=\frac{12}{\frac{3}{2}} ⇒$z$2^{x}=\frac{12.2}{3}⇒ 2^{x}=\frac{24}{3} ⇒ 2^{x}=2^{3} <span>⇒ </span>x=3$