Question

How do you solve the function y = 2.5^x for y=20 

Answer 1

$y=2.5^x;\ y=20\\\\2.5^x=20\\\\log_{2.5}2.5^x=log_{2.5}20\\\\x=log_{2.5}20\\\\x=log_{2.5}(2.5\cdot8)\\\\x=log_{2.5}2.5}+log_{2.5}8\\\\x=1+log_{2.5}8$