Question

$2^{x} +2^{x+1}+2^{x+2}+2^{x+3}= \frac{15}{2}$

Answer 1

$2^x.2=2^{x+1} \\ \\ 3^2.3^5=3^{2+5}=>3^7$

sacou a propriedade? bases iguais repete e soma os expoentes.

n=4
a1=2^x
r=2
Sn=15/2

$an= \frac{a1.(1-q^n)}{1-q} \\ \\ \frac{15}{2}= \frac{2^x.(1-2^4)}{1-2} \\ \\ \frac{15}{2}= \frac{2^x.(1-16)}{-1} \\ \\ -15=2.2^x.(-15) \\ \\ 1=2.2^x \\ \\ 2^x= \frac{1}{2} \\ \\ 2^x=2^{-1} \\ \\ x=-1$