A=5+5^2+5^3+................+5^2017. Tìm x để 4A+5=5^x

(7^1997-7^1995):(7^1994.7)

(2^8+8^3):(2^5.2^3)

A=5+5^2+5^3+................+5^2017
tìm x để 4A+5=5^x