Schönen Abend! Ich benötige eure Hilfe: 3^(x-1)*5^x=90

Guten Abend !

 3^(x-1)*5^x=90        logarithmieren !

(x-1)*log(3)+x*log(5)=log(90)

x*log(3)-log(3)+x*log(5)=log(90)

x*(log(3)+log(5))=log(90)+log(3)

$x=\frac{log(90)+log(3)}{log(3)+log(5)}$        $=2,0673257$         

15^x=270             log(270)/log(15) = 2.0673257669742413

Probe:  3^1.0673257*5^2.0673257-90 = -0.00001       

Gruß radix  !