Question

Логарифмы!
$5^{2lgx}$-$4x^{lg5}$=5

Answer 1

$5^{2lgx}-4x^{lg5}=5\\5^{2lgx}-4*5^{lgx}=5\\5^{lgx}=t,t\ \textgreater \ 0\\t^2-4t-5=0\\D=16+20=36\\t_1=\frac{4+6}2=10\\t_2=\frac{4-6}2=-1,t\ \textgreater \ 0\\5^{lgx}=10\\lgx=log_510\\x=10^{log_510}$