Question

5 la puterea x-1 + 5 la puterea x-2 + 5 la puterea x-3 = 775​

Answer 1

$5^{x-1}+5^{x-2}+5^{x-3}=31*5^2\\5^x*5^{-1}+5^x*5^{-2}+5^x*5^{-3}=31*5^2\\5^x(1/5+1/25+1/125)=775\\5^x(25+5+1/125)=775\\5^x*31/125=775\\5^x=775*125/31\\5^x=3125\\5^x=5^5\\x=5$